Sony LCD projetion screen TV screen spot

I have had my Sony TV, 50" LCD projection screen, for about a year. I have recently noticed a small very slight reddish spot in the center right of the TV when the screen is black. It almost looks like the residual effects of when someone put a magnet to a CRT monitor. Any idea what this is, or if it is a huge problem?

I don't notice it when there is something on the screen.

Thanks for your answeres