I noticed it yesterday in the morning when I was eating breakfast. I can't feel the bump or tell that it's even there unless I'm eating something, then it feels unpleasant but doesn't really "hurt."
It's a bit smaller than a dime I'd say, and can't really be seen with the naked eye, no discoloration its just the normal pinkish color of the rest of the hard palate. It's hard at first, but if you apply a small amount of pressure it feels as if its filled with liquid or something.
It appeared yesterday which is when the cold I'd had died out, so chances are it's nothing but doesn't hurt to be sure!