deep river spot with "obvious" aces $10-$20

[RoundTower]

OK I don't post many hand histories but this was an interesting spot. The guy on my left is badly on tilt, he has been popping it a lot preflop and recently got it all in three ways on the flop with four undercards and an 8 high flush draw, this is where I got my stack. Other guy is an OK semi-reg, not great, I forget how he got his stack. My image is probably aggro but not stupidly so.

what do you make of his river bet?

GAME #653777777: Omaha PL $10.00/$20.00 2007-09-12 11:11:11
Table Fort Lauderdale
Seat 1: deep villain ($5,959.00 in chips)
Seat 5: RoundTower ($7,619.15 in chips) DEALER
Seat 6: tilty villain ($1,856.00 in chips)
Seat 8: BB ($2,036.00 in chips)
Seat 10: UTG ($2,000.00 in chips)
tilty villain: Post SB $10.00
BB: Post BB $20.00
UTG: Post BB $20.00
*** HOLE CARDS ***
Dealt to RoundTower 3 [img]/images/graemlins/club.gif[/img] K [img]/images/graemlins/spade.gif[/img] A [img]/images/graemlins/spade.gif[/img] A [img]/images/graemlins/diamond.gif[/img]
UTG: Check
deep villain: Call $20.00
RoundTower: Raise to $110.00
tilty villain: Raise to $200.00
BB: Fold
UTG: Fold
deep villain: Call $180.00
RoundTower: Raise to $840.00
tilty villain: Call $640.00
deep villain: Call $640.00
*** FLOP *** 2 [img]/images/graemlins/heart.gif[/img] 2 [img]/images/graemlins/spade.gif[/img] 5 [img]/images/graemlins/heart.gif[/img]
tilty villain: Check
deep villain: Check
RoundTower: Bet $1,017.00
tilty villain: Fold
deep villain: Call $1,017.00
*** TURN *** 6 [img]/images/graemlins/diamond.gif[/img]
deep villain: Check
RoundTower: Check
*** RIVER *** K [img]/images/graemlins/heart.gif[/img]
deep villain: Bet $1,040.00
RoundTower: