Just thought I'd chime in my 2 cents worth. I know people have a tendency to overvalue top pair but you guys weren't exactly playing 30-60 dollar NL, 50 cent 1 dollar is chump change and perhaps he was thinking that you had AK and paired your king and were overvalueing your pair. I don't think it was completely irrational of him to cap the betting with that uncoordinated board. No straight or flush either on the flop.