and I'm probably just worrying over nothing, but here it goes. Just this evening I was lo0oking in the mirror and noticed that one of the big molars on my upper right side is half discolored. The bottom half of the tooth is darked than the upper half. Does anyone else have this, and should I be worried? Could I just be seeing a filling or something? Thanks in advance to all who reply.

If it has an amalgam filling in it, then that's probably what you are seeing.