If you haven't seen rainbows on this set, and don't want to, stop reading now...
**Disclaimer: Don't blame me if you read on and watch the scene I point out, and don't like the results***
I'm evaluating this set, and tonight I watched Attack of the Clones. About midway through the movie I started seeing the rainbow effect (never saw it before, but knew immediately what it was), and near the end of the movie there was a scene that showed the effect despite my best efforts not to see it.
Scene 47, after the Count gets off his ship and meets Darth Sidious, there is a scene where he and Sidious start walking together (Sidious says 'You have done well'). There is a light source behind the head of the Count. If you don't see a separation of colors looking from the Count to Sidious, be happy. In this mostly dark scene, my eyes naturally follow the conversation from man to man and the light source in the scene amplifies the effect.
To me, the distracting part isn't the actual sight of the color separation, it's the second after where my brain says 'wtf was that'. Perhaps this goes away with time.