Am I a total fish?

Pokerstars 200+15 buy in, $500k guaranteed tourney
I played a satellite and won my way into this tourney. My first time playing at such a high lvl.

Early in the tourney, I get dealt 9[img]/images/graemlins/spade.gif[/img]9 [img]/images/graemlins/club.gif[/img] in middle position, blinds are at 15/30. I have a 2k chip stack, which is 500 off the avg. 1 loose limper UTG (2.2K chips) . Everybody else folds. I raise to 120 (4x bb). Everybody folds except BB (tight player 2.4K) who calls.

Flop comes 6 [img]/images/graemlins/spade.gif[/img]9 [img]/images/graemlins/spade.gif[/img]K [img]/images/graemlins/diamond.gif[/img]
UTG makes 2/3 pot size bet. From my read on him, he continually bluffs with these typs of bets. I call in hope of raising UTG on the turn. Surprisingly SB raises to 600. UTG folds. I pause and put him on top 2 pair. In the back of my mind I'm also thinking he flopped a set. But since he didn't raise from BB I'm thinking a smaller set. I push all in. BB calls and turns over 2 Kings.

Since this was my first high buyin no limit tourney, just wondering if I overplayed my medium set? What do you guys think?