AQ outdrawn, with some wierd betting

[bilbo-san]

Party Poker 1/2 Hold'em (10 handed). I have no read on UTG, he just sat down.

Preflop: Hero is CO with A[img]/images/graemlins/diamond.gif[/img], Q[img]/images/graemlins/heart.gif[/img].
UTG calls, UTG+1 folds, UTG+2 folds, MP1 folds, MP2 folds, MP3 calls, Hero raises, Button folds, SB folds, BB calls, UTG calls, MP3 folds.

Pretty standard imho.

Flop: (7.50 SB) A[img]/images/graemlins/club.gif[/img], Q[img]/images/graemlins/club.gif[/img], 5[img]/images/graemlins/spade.gif[/img] <font color="blue">(3 players)</font>
BB checks, UTG bets, Hero raises, BB calls, UTG calls.

I felt no neet so slow play this with 2 clubs on the board.

Turn: (6.75 BB) 9[img]/images/graemlins/spade.gif[/img] <font color="blue">(3 players)</font>
BB checks, UTG bets, Hero raises, BB folds, UTG calls.

The bet very much surprised me but perhaps the 9 gave him two pair?

River: (10.75 BB) 2[img]/images/graemlins/spade.gif[/img] <font color="blue">(2 players)</font>
UTG bets, Hero calls.

Huh? I was at a loss here, I saw the flush of course, but couldn't believe anyone on a flush draw would have bet that turn. So I felt I had to call. A loose call?

Final Pot: 12.75 BB
Hero lost $10 [ Ad Qh ] [ two pairs, aces and queens -- Ad,Ac,Qh,Qc,9s ]
UTG won $24.50, net +$14.50 [ Js Qs ] [ a flush, queen high -- Qs,Js,9s,5s,2s ]

Should I have known this and folded the river or am I just thinking results-oriented? I still can't figure out his turn bet.