What to do when medium pocket pair is an overpair on the flop?

[Unoriginalname]

This is a $22 STT on the very first hand. I think I probably played this poorly. What should I have done on the flop?

What range of hands do you put UTG with? I figured he didn't have an overpair because he didn't raise preflop. So maybe A7, Ax suited (hearts), or a pocket pair that hit trips.

Party Poker No-Limit Hold'em Tourney, Big Blind is t15 (10 handed) converter (http://www.selachian.com/tools/bisonconverter/hhconverter.cgi)

UTG+1 (t800)
UTG+2 (t800)
MP1 (t800)
MP2 (t800)
MP3 (t800)
CO (t800)
Button (t800)
Hero (t800)
BB (t800)
UTG (t800)

Preflop: Hero is SB with 9/images/graemlins/club.gif, 9/images/graemlins/diamond.gif.
UTG calls t15, UTG+1 calls t15, <font color="#666666">3 folds</font>, MP3 calls t15, <font color="#666666">1 fold</font>, Button calls t15, Hero completes, BB checks.

Flop: (t87.50) 3/images/graemlins/heart.gif, 6/images/graemlins/diamond.gif, 7/images/graemlins/heart.gif <font color="#0000FF">(6 players)</font>
Hero bets t70, BB folds, UTG raises to t140, UTG+1 folds, MP3 folds, Button folds, Hero is all-in t715

[nummy]

Might be my paranoia, but this looks likes the classic case of UTG aces or kings being slowed played. Again though, I am always paranoid when UTG only limps into the action, especially at a $22 table.

[Unoriginalname]

You're right, there are people definitely capable of slow-playing high pocket pairs. Not sure why I immediately dismissed that.

[Unarmed]

Betting the flop here is bad because you'll be folding the best hand to an overplayed A7 way too often, and even if you don't get raised, you're in a real uncomfrtable spot on the turn if called in one or more places. Nice spot for a large C/R given the relatively low chances the hand gets checked around.

(errr... wait, you pushed. Well, at least you didn't lay down the best hand - lol)