[FoxwoodsFiend]

Honestly, if there's ever a time to not be too excited about bottom set it's when the tightest player at the table smooth-calls your flop bet then check-raises barely more than the min. I would immediately slow down, just call, see what he does on the river. Maybe even act like you're considering folding a marginal hand so that he doesn't think he can get too much out of you on the river if he does have you beat at the moment. If he bets the river hard you have to fold, but if he puts in a medium-sized bet you have to call.
By the way, not only is 77 a distinct possibility but so is KK. It's not unheard of for people in the small blind to slow-play KK to a pre-flop raiser looking to trap on any board with no ace and having nobody see it coming if they hit a set. I don't know if villain is that crafty but it's far from out of character for a tight player to try disguising the strength of his hand.