It's just the plastic heating up. Smell any hot running electronic device after it's been on a while. None of them smell good. Take a whiff near the vents on a high powered audio receiver after it's been on a good half hour or more. They stink bad. LOL!
As long as you're TV isn't smoking I wouldn't be worried.
Of course, I got it modified with the TK-427, which cheeks it up another, maybe, 3 or 4 quads per channel.
Actually, I would try to avoid smelling it-- if it really is a normal smell, it is probably due to outgassing of the plastics and other components. Just like a new car or new shower curtain. But- those fumes can be bad for you so I wouldnt stick my nose right in there until the outgassing has slowed down.