$11 NLTRN - TP w/36o facing min-RR - unsure of this one

[pokercurious]

This is the 4th hand, first 3 went like this:
1. I raise Q5o, he calls, I cbet, he folds
2. He raises, I fold 38o
3. I raise A6o, he folds

Blinds: t10/t20
2 players

Stack sizes:
SB: t1440
Hero: t1560

Pre-flop: (2 players) Hero is BB with 6[img]/images/graemlins/heart.gif[/img] 3[img]/images/graemlins/spade.gif[/img]
SB calls t10 <font color="aaaaaa">(pot was t30)</font>, Hero checks.

Flop: 2[img]/images/graemlins/heart.gif[/img] 6[img]/images/graemlins/spade.gif[/img] 5[img]/images/graemlins/diamond.gif[/img] (t40, 2 players)
Hero checks, <font color="#cc0000">SB bets t60</font>, <font color="#cc0000">Hero raises to t180</font>, <font color="#cc0000">SB raises to t300</font>, Hero ???

Pretty much readless (unless you consider a -3% SS ROI at an average stake of $22 over 400 games to be a read), I'd assume that the RR means he has at least a pair, or at the very least a strong draw.

The problem is, I'm not sure how much to expect this means a bluff. The PF limp makes me think it's not a premium hand, but he could have very easily limped a hand that had me beat, including small PP's and weak A's, K's, Q's, J's, etc.

My flop raise feels ok, because he's just overbet a small pot, which is often code for "you don't really want it, it's a tiny pot, just give it to me and move on."

Do Villains bet sets like this? Overpairs? Am I being confused by nothing and this is in fact an easy fold? Gah.