Anyone else seeing that the bottom of their 4S screen (when held in portrait mode, home button on bottom) is noticeably brighter than the top of the screen? It is on mine. Not really a deal breaker but it's a little annoying. Didn't have that issue on my 1st gen, 3G, or 3GS. Especially noticeable in iBooks where you have a solid white screen, or on many web pages.