Get estimates for the repair. At best they'll replace a top cover screen, at worst they'll tell the LCD needs changing which is more than a new set OOW (out of warranty.)
In the center of my TV (55 inch magnavox) there is something that looks like a grey smudge. I thought it was a smudge but after cleaning the screen I realized it was under the screen. I can only see it when bright colors appear not the darker ones. I've tried to change all the settings but nothing works.

Chowhound
Comic Vine
GameFAQs
GameSpot
Giant Bomb
TechRepublic