MUST I call all-in river bet with A-high flush?

81-person turbo satellite to WCOOP is just underway (10-20 hands). No reads on anyone yet, but the table has been tight.

Is there any way I lay this down on the river? Also, was my river bet OK?

PokerStars No-Limit Hold'em Tourney, Big Blind is t30 (9 handed) converter

Button (Villain) (t1525)
SB (t1595)
BB (t1540)
UTG (t1510)
UTG+1 (t1470)
Hero (t1470)
MP2 (t1520)
MP3 (t1420)
CO (t1450)

Preflop: Hero is MP1 with 8[img]/images/graemlins/spade.gif[/img], A[img]/images/graemlins/spade.gif[/img].
UTG calls t30, <font color="#666666">1 fold</font>, Hero calls t30, <font color="#666666">3 folds</font>, Button (Villain) calls t30, SB completes, BB checks.

Flop: (t150) 2[img]/images/graemlins/diamond.gif[/img], 3[img]/images/graemlins/spade.gif[/img], 2[img]/images/graemlins/spade.gif[/img] <font color="#0000FF">(5 players)</font>
SB checks, BB checks, <font color="#CC3333">UTG bets t90</font>, Hero calls t90, Villain calls t90, SB folds, BB folds.

Turn: (t420) J[img]/images/graemlins/heart.gif[/img] <font color="#0000FF">(3 players)</font>
<font color="#CC3333">UTG bets t90</font>, Hero calls t90, Villain calls t90.

River: (t690) 4[img]/images/graemlins/spade.gif[/img] <font color="#0000FF">(3 players)</font>
UTG checks, <font color="#CC3333">Hero bets t300</font>, <font color="#CC3333">Villain raises to t1315</font>, UTG folds, Hero ???