Ahh, I think you're right - I must have inadvertently been hitting the light sensor with my thumb.

But, I still have the color issue. The N810 definitely doesn't have as 'clean' of a white than my (2) N800s I have here in front of me. If this is normal, I can live with it. But without returning the N810 for a replacement, I'm not certain how I can find out if this is normal. Hopefully someone can offer their experience.