[El_Hombre_Grande]

This looks like a simple value bet to me; it makes sense that he didn't want to risk a check. Your fish was probably "walking the dog" with a made flush or spiked a queen while never quite sure what he was doing.

In any event, its marginal. Pot odds, yeah, but you almost have to be beat. Passive fish is now running daring river bluffs? Naw.