raise this river?

[fairness]

Party Poker 0.5/1 Hold'em (10 handed)

both players here are pretty passive, thought maybe utg's river bet meant fullhouse, also he was just callin along with me so maybe he's on a flush draw as well... i don't know this felt weak.

Preflop: Hero is Button with 4/images/graemlins/heart.gif, 6/images/graemlins/heart.gif. CO posts a blind of $0.5.
UTG calls, UTG+1 calls, UTG+2 folds, MP1 folds, MP2 calls, MP3 calls, CO (poster) checks, Hero calls, SB folds, BB checks.

Flop: (7.50 SB) 3/images/graemlins/heart.gif, A/images/graemlins/club.gif, T/images/graemlins/heart.gif <font color="blue">(7 players)</font>
BB folds, UTG checks, UTG+1 checks, MP2 checks, <font color="CC3333">MP3 bets</font>, CO folds, Hero calls, UTG folds, UTG+1 calls, MP2 folds.

Turn: (5.25 BB) Q/images/graemlins/diamond.gif <font color="blue">(3 players)</font>
UTG+1 checks, <font color="CC3333">MP3 bets</font>, Hero calls, UTG+1 calls.

River: (8.25 BB) Q/images/graemlins/heart.gif <font color="blue">(3 players)</font>
<font color="CC3333">UTG+1 bets</font>, MP3 calls, Hero calls.

Final Pot: 11.25 BB

[CWsports]

I raise the river. It looks like UTG+1 has a Q and was afraid to bet the turn because of the A on the flop.