Fold a set early on 3-suited board?

[revots33]

Very 1st hand of $11 tournament on Stars. I've got 5 [img]/images/graemlins/club.gif[/img]5 [img]/images/graemlins/heart.gif[/img]and limp in middle position. SB calls, BB checks.

Flop comes K [img]/images/graemlins/diamond.gif[/img]5 [img]/images/graemlins/diamond.gif[/img]2 [img]/images/graemlins/diamond.gif[/img].

SB, BB check. I bet 150. SB goes all-in. BB folds.

Do I fold here seeing as how it's only the 1st hand, and he's representing a flush? Or should I call figuring a)I might have a semi-bluff beat and b)even if he's got the flush I might hit my full house.

And, was my 150 bet incorrect in this spot? Maybe I should have bet less, or even checked to see the turn?

I try to play extra tight in the early rounds but I always get confused when I have a strong hand (but not the nuts) and someone comes over the top.