Whilst it's true that bug reports should be filed, honestly sometimes it feels like asking publicly if other users are getting the same issues gets more done, or at least helps in knowing that it isn't anything to do with the app in particular and it can confirm whether it's a bug with iOS or not.
My app is still getting this with the latest iOS 1.3.1 it doesn't happen much and I haven't managed to trigger it myself, but I can see that (1 every 5K) users has it once in a blue moon, that still isn't acceptable though.
I only use GLKViewController with GLKView and everything I read regarding this issue seemed to suggest that it could be due to OpenGL drawing whilst the app is in the background, the docs seem to suggest that this should never happen when using GLKViewController+GLKView, is it safe to assume that GLKView internally calls glFinish() on applicationWillResignActive?
Was this ever looked at?