Too aggressive with AA in the BB?

[kem]

Haven't seen AA in ~400 hands, then get dealt it on my very first hand tonight, as BB.

Party Poker 0.50/1 Hold'em (10 handed)

Preflop: Hero is BB with A[img]/images/graemlins/heart.gif[/img], A[img]/images/graemlins/spade.gif[/img].
UTG calls, UTG+1 folds, UTG+2 folds, MP1 folds, MP2 calls, MP3 folds, CO calls, Button calls, SB completes, <font color="CC3333">Hero raises</font>, UTG calls, MP2 calls, CO calls, Button calls, SB calls.

Flop: (12 SB) 2[img]/images/graemlins/heart.gif[/img], 7[img]/images/graemlins/club.gif[/img], T[img]/images/graemlins/diamond.gif[/img] <font color="blue">(6 players) </font>
SB checks, <font color="CC3333">Hero bets</font>, UTG calls, MP2 calls, CO calls, Button calls, SB calls.

Turn: (9 BB) 4[img]/images/graemlins/club.gif[/img] <font color="blue">(6 players) </font>
SB checks, <font color="CC3333">Hero bets</font>, UTG calls, MP2 calls, CO calls, Button folds, SB folds.

River: (13 BB) 7[img]/images/graemlins/spade.gif[/img] <font color="blue">(4 players) </font>
<font color="CC3333">Hero bets</font>, UTG calls, MP2 calls, <font color="CC3333">CO raises</font>, Hero calls, UTG calls, MP2 folds.

Final Pot: 20 BB
<font color="#990066">Main Pot: 20 BB, between UTG, CO and Hero.</font>

I thought a long time on the river before making the call.. With a pair of 7's on the board, and 3 other guys in the pot, odds are one has me beat, right?