when such a tight passive player leads out, just watch out in this spot, he had you beat for sure with at least high kickers like J or Q. 50%/50% i 'd fold/call on the flop, depending on my comfortable level as played. On the river, you should call his small bet given huge pot odds and he did check on the turn, IMO. also, if he did have set or high kicker, just take a note on this guy after finding out what he had.