Please rate my play against the double check-raise

[Shoe]

PokerStars 10/20 Hold'em (6 handed) Hand History Converter Tool from FlopTurnRiver.com (Format: 2+2 Forums)

Preflop: Hero is CO with 9[img]/images/graemlins/club.gif[/img], 9[img]/images/graemlins/spade.gif[/img].
<font color="#CC3333">UTG raises</font>, <font color="#CC3333">MP 3-bets</font>, <font color="#CC3333">Hero caps</font>, <font color="#666666">3 folds</font>, UTG calls, MP calls.

Flop: (13.50 SB) T[img]/images/graemlins/spade.gif[/img], 6[img]/images/graemlins/heart.gif[/img], 6[img]/images/graemlins/club.gif[/img] <font color="#0000FF">(3 players)</font>
UTG checks, MP checks, <font color="#CC3333">Hero bets</font>, <font color="#CC3333">UTG raises</font>, <font color="#CC3333">MP 3-bets</font>, Hero folds, UTG calls.

Turn: (9.25 BB) 3[img]/images/graemlins/club.gif[/img] <font color="#0000FF">(2 players)</font>
UTG checks, MP checks.

River: (9.25 BB) J[img]/images/graemlins/heart.gif[/img] <font color="#0000FF">(2 players)</font>
UTG checks, MP checks.

Final Pot: 9.25 BB

UTG was fairly new but seemed to be a good player. I would have called him down, as players like him typically check-raise me there, but the MP check-raised the check-raise which scared me off. However MP is an absolute lunatic, 60/40 making ridiculous bets, check-raises, and call downs. Was I being too timid here?