Primitive Cube Vertices Different

I've been working on UV mapping within Unity for a project I'm working on and I found and used the script found here: http://answers.unity3d.com/questions/306959/uv-mapping.html

Now this works perfectly fine on Windows, but when I try and do the exact same thing on my Mac, things don't work right, the texture on the sides of the cube get split 'incorrectly'.

In this code:

 private Vector2[] theUVs;

 void Start() 
 {
     theMesh = transform.GetComponent<MeshFilter>().mesh;
     theUVs = new Vector2[theMesh.uv.Length];
     theUVs = theMesh.uv;

     SetUVs();
 }

the array 'theUVs' has the same values in PC vs Mac. But in the mac version I get:

I can fix it here:

 // OLD: LEFT   19   17   16   18
 //theUVs[19] = new Vector2( uvsLeft.x, uvsLeft.y );
 //theUVs[17] = new Vector2( uvsLeft.x + uvsLeft.width, uvsLeft.y );
 //theUVs[16] = new Vector2( uvsLeft.x, uvsLeft.y - uvsLeft.height );
 //theUVs[18] = new Vector2( uvsLeft.x + uvsLeft.width, uvsLeft.y - uvsLeft.height );
 
 // LEFT   19   17   16   18
 theUVs[17] = new Vector2( uvsLeft.x, uvsLeft.y );
 theUVs[18] = new Vector2( uvsLeft.x + uvsLeft.width, uvsLeft.y );
 theUVs[16] = new Vector2( uvsLeft.x, uvsLeft.y - uvsLeft.height );
 theUVs[19] = new Vector2( uvsLeft.x + uvsLeft.width, uvsLeft.y - uvsLeft.height );

The question really is, why is it different between the two systems? Why do I have to change it?

Thanks for your help