Thanks JamieCatheryn. It definitely looks like there might be some little tooth buds starting to poke through in a couple of places. Hard to be sure, as I never examined his gums super closely before this. From what I've gathered, teething this early is not all that rare. For the most part, he seems to be handling it OK. Still slept well last night, not too fussy this morning (although slightly more than normal). Definitely not preventing him from eating! I just hope he gets through it OK. I hate to see him in pain.
My daughter had teething symptoms around 3 months and we were positive she was teething. Her first tooth didn't pop until around 9 months. Someone told me that they start teething much earlier than the teeth pop through as the teeth move up through the jaw. So they can be fussy and drooly for no apparent reason. While it's possible he's teething, I wouldn't be surprised either if he ends up popping teeth later. I hope he feels better either way.