I bought a Samsung PN58C6400 in December 2010. Within the last couple of months, I have started to notice a faint purpleish horizontal bar appearing toward the top of the screen. I've only noticed it in the same location and it seems to happen on mostly white backgrounds. I have run the burn in protection a couple of times on the TV and it still appears. I'm looking for help on what this might be and how I can fix it? Thanks.