NL 100 - I cannot believe I just folded this set

[vizer02]

Okay, villain is mliang, a 12/3/1 TAG. I don't think I've ever seen him get out of line, nor would I think so with his stats. Therefore, I cannot see him pushing a flush draw or a strong ace. Also, preflop I probably raise this 75% of the time, cold call 25% of the time. It's also funny because a few weeks ago I said on here I hardly ever fold sets, and here I am folding one because it seemed so obvious to me that he either had A,A or 7,7. The one thing that almost kept me from folding was that he knows I play combo draws fast, and possibly he did just have a strong ace.

Would you have folded?

Full Tilt Poker - No Limit Hold'em Cash Game - $0.50/$1 Blinds - 9 Players - (http://www.legopoker.com http://www.legopoker.com/hh)

SB: $35.85
BB: $120.30
UTG: $105.25
UTG+1: $33.35
MP1: $100.30
MP2: $84.35
Hero (MP3): $170.80
CO: $71.10
BTN: $101.10

Preflop: Hero is dealt 3d 3s (9 Players)
2 folds, MP1 calls $1.00, MP2 folds, Hero calls $1.00, 2 folds, SB calls $0.50, BB checks

Flop: ($4) 7c 3h Ac (4 Players)
SB checks, BB bets $4.00, MP1 raises to $10.00, Hero raises to $25.00, 2 folds, MP1 raises to $40.00, Hero folds
Uncalled bet of $15.00 returned to MP1

Pot Size: $58.00 ($2.90 Rake)