Strange smearing on texture with unity 4.3.4

So I'm having a weird issue using a scrolling texture script on a sprite in 4.3.4. The sprite was an export from max, but that shouldn't matter. The script I'm using, I found online which scrolls the verts on the sprite.

This works fine in Unity 4.2.1f, but once I upgrade I get this smearing effect when it's suppose to loop.

I've tried various shaders to no avail. I'm not understanding what could be causing this?

here's the script it's using...

 #pragma strict
 
 //scroll main texture based on time
  
 var scrollSpeed:         float = .5;
 var offset:             float;
 var rotate:             float;
  
 function Update ()
 {
     offset+= (Time.deltaTime*scrollSpeed)/10.0;
     //scrolls right to left
     //renderer.material.SetTextureOffset ("_MainTex", Vector2(offset,0));
     //scrolls bottom to top
     renderer.material.SetTextureOffset ("_MainTex", Vector2(0, offset));
 }