Flop Two Pair In BB

[GypTheCat]

After two months or so of lurking about and trying to absorb as much info as possible, played my first few $11s yesterday. Of course, in the midst of the game, much of what I thought I'd learned evaporated. So let's ramp up the learning process with actual hands I played before I get into too many bad habits....

This one bothers me: my fold seems weak.

PokerStars Game #1915619951: Tournament #9062910, Hold'em No Limit - Level III (25/50) - 2005/06/17 - 01:00:40 (ET)
Table '9062910 1' Seat #4 is the button
Seat 1: dartagnan (2750 in chips)
Seat 2: luckluke (1870 in chips)
Seat 3: jasonk182 (1245 in chips)
Seat 4: Chieftomcat (2110 in chips)
Seat 5: fghy (1510 in chips)
Seat 6: GypTheCat (2530 in chips)
Seat 8: Wall88St (1485 in chips)
fghy: posts small blind 25
GypTheCat: posts big blind 50
*** HOLE CARDS ***
Dealt to GypTheCat [3c 8c]
Wall88St: folds
dartagnan: folds
luckluke: folds
jasonk182: folds
Chieftomcat: calls 50
fghy: calls 25
GypTheCat: checks
*** FLOP *** [8s 3h 6c]
fghy: bets 150
GypTheCat: raises 250 to 400
Chieftomcat: raises 1660 to 2060 and is all-in
fghy: calls 1310 and is all-in
GypTheCat: folds
*** TURN *** [8s 3h 6c] [Jh]
*** RIVER *** [8s 3h 6c Jh] [2d]
*** SHOW DOWN ***
fghy: shows [9h 9c] (a pair of Nines)
Chieftomcat: shows [Qh Qc] (a pair of Queens)
Chieftomcat collected 3470 from pot

My thought was one of the two had hit a set...that they had limped in with a small pair. Am I just being weak and should I take the chance to greatly increase my stack in this situation?