I got a replacement for my black Lumia 900, which had a dead pixel, and the replacement has this purple problem, whereas my original phone does not. I chatted online with a Nokia rep who said they had not heard of the issue, but then called in to Nokia and spoke with someone who said he had heard of it, and he assumed they would release a fix for it, but when pressed he said he was not sure if or when that would happen.
When I said I'd likely return it b/c I just received it, he said that would probably be the best course of action.
I'm a bit concerned b/c I got mine from Amazon and can't be sure the next replacement won't have the same problem. I'm guessing it might be an issue of the lesser of two evils: dead pixel on my original phone vs. purple cast on a replacement.
What is interesting to me too is that my original phone shows fingerprints like crazy - on both the screen and the body - but the replacement with the purple problem doesn't show fingerprints anywhere, as if it has some sort of fingerprint-proof treatment all over it. Not sure if that could have something to do with the purple problem? Definitely a shame, as I like how the replacement doesn't show fingerprints. Also, the replacement came with a green dot on the box.