GUI.Rect() 1 pixel offset? [JS]

Hello, I am having a very odd error where I am drawing a Rect and it appears to be offset 1 pixel to the left (-x) and one pixel up (+y). I am making a pixel perfect 2D game. (I have checked the "pixel perfectness" in photoshop and everything checks out. (E.G. My tiles are 64x64 and the Rect being drawn is 64x64.

Here is the code I am using to draw the Rect:

     var pos = Camera.main.WorldToScreenPoint(selectorPos);
     DrawQuad(Rect(pos.x-32,Screen.height - (pos.y+32),64,64),Color.blue);//TODO: Figure out why it's -31 not -32

 function DrawQuad(position : Rect, color : Color) {
     var texture : Texture2D = new Texture2D(1, 1);
     texture.SetPixel(0,0,color);
     texture.Apply();
     GUI.skin.box.normal.background = texture;
     GUI.Box(position, GUIContent.none);
 }

Here are the results.

When Rect(pos.x-31,Screen.height - (pos.y+31),64,64),Color.blue); we get the correct look:

When Rect(pos.x-32,Screen.height - (pos.y+32),64,64),Color.blue); we get the mathematically correct but wrong looking result:

What am I missing here?