I'm not even sure how to explain what I'm seeing, so I'll post a couple of images. I've stripped the UI down to a fairly simple hierarchy with a UIRoot, UICamera, and a button. In the example here the UIPanel script is attached to UIRoot--this may be part of the problem, but I have seen the same thing with a traditional game object hierarchy with UIPanel under UICamera.
Anyway, here's a before and after. There's no user interaction (besides possibly clicking the button a couple of times) and after about 30s the button warps into the second image. Usually it completely disappears, but this time I managed to see this more rare behaviour. Even when I see the warped button it will eventually disappear entirely within a minute or so. This is taken from a Samsung Galaxy SIII. I've never seen this in the editor. I believe we've repo'ed this on iPhone as well. The GUI text is printing out the object hierarchy and (in this case) the layer that each object is attached to. I've done debugging outputting the transforms (position, scale, rotation) of each object and those stay the same before and after the warping/disappearing.
We're using the latest Unity beta (4.3.0b1) and the latest licensed version of NGUI.
Any thoughts about what could possibly be causing this would be most helpful.
Thanks!
Ryan