Issue w/ Samsung 6187?????

I had this set for about a week. It was a warranty replacement for my old CRT. The Samsung 6187 has been wonderful all week and then this morning my son was watching cartoons and a dark shadow appeared on the lower left corner of the screen. The shadow is very dark and is an odd shape that never changes or moves. It also appears on DVD as well as Satellite. I hope it is just a lamp issue, but really have no idea. Please help me w/ any suggestions.