I have had the slight shading on the right side of my screen on the n800 since I first turned it on. I have seen this before on other mobile devices. After a while I do not notice it unless I look for it. For me it is not enough of a problem to return it.
I also noticed over time that I now have to press a little harder to scroll on the lower middle right side. But again, at this point it has not been enough of a problem for me to return it. Still have 9 months to decide before the waranty expires.