$25 NL... Fold set in this spot ?

[FearNoArt]

PokerStars No-Limit Hold'em, $0.25 BB (6 handed) Hand History Converter Tool from FlopTurnRiver.com (Format: 2+2 Forums)

UTG ($17.80)
Hero ($45.80)
CO ($28.05)
Button ($4.75)
SB ($4.70)
BB ($18.90)

Preflop: Hero is MP with 3[img]/images/graemlins/heart.gif[/img], 3[img]/images/graemlins/diamond.gif[/img].
<font color="#666666">1 fold</font>, Hero calls $0.25, <font color="#666666">3 folds</font>, BB checks.

Flop: ($0.60) J[img]/images/graemlins/club.gif[/img], 3[img]/images/graemlins/spade.gif[/img], T[img]/images/graemlins/heart.gif[/img] <font color="#0000FF">(2 players)</font>
BB checks, Hero checks.

Turn: ($0.60) 5[img]/images/graemlins/spade.gif[/img] <font color="#0000FF">(2 players)</font>
<font color="#CC3333">BB bets $3</font>, Hero ?



This play baffles me, BB is a timid rock 7/1/0. I've played approx 100 hands against him , he never makes any moves, typical rock. My table stats are 17/4/2 and have showndown winning hands and laid down when I figured I was beat. I've seen him limp JJ in SB. I slow play this flop not wanting to scare rock out. His turn bet looks like a set overbetting pot, trying to look like a loose donk or he's trying to represent top pair trying to shut down flush draw while actually holding a set. Problem is he never makes plays like this. Can this be anything but a set ? Does Villain play 2 pair like this ? Is this a rocktard donkbluff ?