AK in 35+3 rebuy tournament

[strkvam]

I have about 5000 in chips and everyone at the table cover me.

I`m UTG+1 and raises up to 600 with A [img]/images/graemlins/diamond.gif[/img]K [img]/images/graemlins/spade.gif[/img] SB and BB calls.
Flop: 8 [img]/images/graemlins/club.gif[/img]10 [img]/images/graemlins/spade.gif[/img]Q [img]/images/graemlins/spade.gif[/img] check, check, and I check. ( maybe I should bet the flop? )

Turn: 3 [img]/images/graemlins/diamond.gif[/img] check, check check again.
River: j [img]/images/graemlins/spade.gif[/img] SB checks, BB bets 600, I raise to 1800, SB re-raises to 5500, and BB calls, I have now 2200 chips left. I did hit my gutshot, but I was sure atleast one of them had the flush so I throw away my nut-straight. ( I realize that it was a bad fold because of the odds,but I did anyway)

SB shows K9 for a K high straight and BB mucks...wtf?

what and were should I play different? Please comment!

Best Regards