I have a Samsung PN50C490 mfg. in 2010 and lately have been noticing what appears to be screen burn. When the screen is black there appears to be the color red bleeding through the black. Sorry i don't have a pic but an example would be a picture with a red background with black painted over it. If you were to wash some of the black off, the red would show through. It looks as if it has started in the center of the screen and is not noticeable except during total black background especially just after power on but never completely goes away and does seem to get better at times. It also doesn't actually look like an image that has burnt in because it has no definitive shape to it. Any ideas other than screen burn?