Hand from stupor, fold the river straight?

[BrandiFan]

I just won the last 2 hands in a row without showing down and pick up AJ. I don't bet turn or flop cause I am perfectly happy to check this down and show that I am raising decent hands and villian has made some aggressive calls... Standard fold on river?

Poker Stars, $150 + $12 NL Hold'em Tournament, 15/30 Blinds, 9 Players
LeggoPoker Hand History Converter

BB: 3,805
UTG: 2,325
UTG+1: 3,075
UTG+2: 2,850
MP1: 3,400
MP2: 2,745
Hero (CO): 6,105
BTN: 3,140
SB: 2,845

Pre-Flop: (45) A[img]/images/graemlins/club.gif[/img] J[img]/images/graemlins/spade.gif[/img] dealt to Hero (CO)
5 folds, <font color="red">Hero raises to 90</font>, BTN folds, SB calls 75, BB folds

Flop: (210) Q[img]/images/graemlins/heart.gif[/img] 4[img]/images/graemlins/club.gif[/img] 2[img]/images/graemlins/heart.gif[/img] (2 Players)
SB checks, Hero checks

Turn: (210) 3[img]/images/graemlins/diamond.gif[/img] (2 Players)
SB checks, Hero checks

River: (210) 5[img]/images/graemlins/heart.gif[/img] (2 Players)
<font color="red">SB bets 510</font>, Hero folds

Results: 210 Pot
SB mucked and WON 210 (+120 NET)