How would you play this river?

[AlexHoops]

This post led to an interesting discussion over at FCP

Playing against a Fish... his river bet scared me

Party Poker 2/4 Hold'em (10 handed) converter

Preflop: Hero is MP1 with [Ad], [Kd].
2 folds, UTG+2 calls, Hero raises, 6 folds, UTG+2 calls.

Flop: (5.50 SB) [Tc], [3c], [Ks] (2 players)
UTG+2 checks, Hero bets, UTG+2 calls.

Turn: (3.75 BB) [As] (2 players)
UTG+2 bets, Hero raises, UTG+2 calls.

River: (7.75 BB) [5s] (2 players)
UTG+2 bets, Hero calls.

Final Pot: 9.75 BB

Did I miss a bet on the river?