How do you zoom, exactly? NGUI's behaviour was designed with camera ortho size of 1 in mind, so I hope you aren't changing that. That said, I see no reason why even doing that would change the colliders or cause them to not be aligned. Now if you had two widgets on the same game object, then yes, that would cause weird issues like that when you move something and its collider ends up in one place but the visible object ends up in another.