The Bike 200NL flopped set call river?

[ThaHero]

Ok so I really screwed up this hand. I should have posted it the day it happened because now the details are sketchy but I'll try to remember the action exactly.

I have about $300 in front of me UTG+2 with 55 and limp. This table has been limping multi-way preflop a lot, and this hand is no different. 6 people in the hand. I have about the same amount as everyone else except an old guy who is sitting out(he kept falling asleep).

Flop is A 2 5 rainbow. Pot is roughly $25.

Checked to me, I check, it gets checked around. I realize I should probably have bet this but this table had been playing somewhat aggressive on flops and I was hoping to trap an ace with a check raise.

Turn is a K that brings a second [img]/images/graemlins/heart.gif[/img]. I bet 20. Get one caller in the CO and one in the SB.

River is 3. SB check, I check, CO bets 30. Sb folds. I?

Villain is a basic loose-passive. I've only seen him bet with a hand. Seeing him bet, I figure he may have a 4(especially with so many callers preflop). Is a fold too weak-tight? Is a call too loose?