Unity procedural mesh generation UV texture flickering horizontal lines

Here's a build: https://dl.dropboxusercontent.com/u/140141632/temp/web.html If you move along the y axis (w/s) you'll notice that you'll see horizontal blue lines flicker in and out.

I'm using this sprite sheet: https://dl.dropboxusercontent.com/u/140141632/temp/spritesheet.png

I think the problem has something to do with the spritesheet because when I change the color of the blue sprites, it changes the color flicker.

Here is my code used for generating the mesh:

'using UnityEngine; using System.Collections;

[RequireComponent(typeof(MeshFilter))] [RequireComponent(typeof(MeshRenderer))] [RequireComponent(typeof(MeshCollider))]

public class Map : MonoBehaviour {

 int width = 50, height = 50;
 float textureWidth = 4, textureHeight = 4;
 
 void Start () {
     BuildMesh();
     GenerateMap();
 }
 
 void Update () {
     
 }
 
 void BuildMesh() {
     Vector3[] vertices = new Vector3[width * height * 4];
     Vector3[] normals = new Vector3[width * height * 4];
     Vector2[] uv = new Vector2[width * height * 4];
     int[] triangles = new int[width * height * 2 * 3];
     
     for(int y=0; y<height; y++) {
         for(int x=0; x<width; x++) {
             int tl = (y * width + x) * 4;
             
             vertices[tl + 0] = new Vector3(x, -y, 0);
             vertices[tl + 1] = new Vector3(x + 1, -y, 0);
             vertices[tl + 2] = new Vector3(x + 1, -y - 1, 0);
             vertices[tl + 3] = new Vector3(x, -y - 1, 0);
             
             uv[tl + 0] = new Vector2(0.0f, 0.25f);
             uv[tl + 1] = new Vector2(0.25f, 0.25f); 
             uv[tl + 2] = new Vector2(0.25f, 0.0f);
             uv[tl + 3] = new Vector2(0.0f, 0.0f);
             
             int tri_start = (y * width + x) * 6;
             
             triangles[tri_start + 0] = tl + 0;
             triangles[tri_start + 1] = tl + 2;
             triangles[tri_start + 2] = tl + 3;
             
             triangles[tri_start + 3] = tl + 0;
             triangles[tri_start + 4] = tl + 1;
             triangles[tri_start + 5] = tl + 2;
         }
     }
     
     for(int i=0; i<width * height * 4; i++) {
         normals[i] = Vector3.forward;    
     }
     
     Mesh mesh = new Mesh();
     mesh.vertices = vertices;
     mesh.normals = normals;
     mesh.triangles = triangles;
     mesh.uv = uv;
     
     MeshFilter mf = GetComponent<MeshFilter>();
     mf.mesh = mesh;
 }
 
 void GenerateMap() {
     float xOff = (float)Random.Range(1, 1000000);
     float yOff = (float)Random.Range(1, 1000000);
     
     // 0 = Black empty thing grass maybe; 1 = forest; 2 = moutain; 3 = water
     int[,] tiles = new int[50,50];
     for(int y=0; y<50; y++) {
         for(int x=0; x<50; x++) {
             tiles[x,y] = 0;
         }
     }
     
     for(int y=0; y<height; y++) {
         for(int x=0; x<width; x++) {
             float noise = Mathf.PerlinNoise(x * 0.2f + xOff, y * 0.2f + yOff);
             if(noise < 0.25f) {
                 tiles[x,y] = 2;
             }
         }
     }
     
     for(int y=0; y<height; y++) {
         for(int x=0; x<width; x++) {
             float noise = Mathf.PerlinNoise(x * 0.15f + xOff, y * 0.15f + yOff);
             if(noise < 0.35f) {
                 tiles[x,y] = 1;
             }
         }
     }
     
     for(int y=0; y<height; y++) {
         for(int x=0; x<width; x++) {
             float noise = Mathf.PerlinNoise(x * 0.08f + xOff, y * 0.08f + yOff);
             if(noise < 0.27f) {
                 tiles[x,y] = 3;
             }
         }
     }
     
     
     for(int y=0; y<50; y++) {
         for(int x=0; x<50; x++) {
             if(tiles[x,y] == 0) {
                 SetTile(x, y, 0, 0);    
             }
             
             else if(tiles[x,y] == 1) {
                 SetTile(x, y, 0, 1);
             }
             
             else if(tiles[x,y] == 2) {
                 SetTile(x, y, 1, 0);    
             }
             
             else if(tiles[x,y] == 3) {
                 SetTile(x, y, 1, 1);    
             }
         }
     }    
 }
 
 void SetTile2(int x, int y) {
     MeshFilter mf = GetComponent<MeshFilter>();
     Vector2[] uv = mf.mesh.uv;
     int tl = (y * width + x) * 4;
     uv[tl + 0] = new Vector2(0.0f, 0.0f);
     uv[tl + 1] = new Vector2(1.0f, 0.0f); 
     uv[tl + 2] = new Vector2(1.0f, 1.0f);
     uv[tl + 3] = new Vector2(0.0f, 1.0f);
 }
 
 void SetTile(int x, int y, float tx, float ty) {
     //Only works for square sprite sheets, no rectangles
     ty = -ty;
     
     MeshFilter mf = GetComponent<MeshFilter>();
     
     Vector2[] uv = mf.mesh.uv;
     int tl = (y * width + x) * 4;
     
     float textureSize = 1f / textureHeight;
     float startX = tx / textureWidth;
     float startY = ty / textureHeight - textureSize;
     
     uv[tl + 0] = new Vector2(startX + 0.0f, startY + textureSize);
     uv[tl + 1] = new Vector2(startX + textureSize, startY + textureSize); 
     uv[tl + 2] = new Vector2(startX + textureSize, startY + 0.0f);
     uv[tl + 3] = new Vector2(startX + 0.0f, startY + 0.0f);
     
     mf.mesh.uv = uv;
 }

}'