Is this the proper line for a mid to low pair?

[Wired Jokers]

We've been talking lately about mid to low pocket pairs on this board, so here is one for review:

Party 2/4. Villian is slightly loose preflop, otherwise decent.

Hero is dealt 6 [img]/images/graemlins/club.gif[/img] 6 [img]/images/graemlins/diamond.gif[/img]

Preflop: UTG folds, UTG+1 folds, Hero calls, folded to CO (Villian) who raises. BB calls. Hero calls.

Flop (6.5 SB): 9 [img]/images/graemlins/heart.gif[/img] 7 [img]/images/graemlins/heart.gif[/img] 3 [img]/images/graemlins/spade.gif[/img]

BB checks, Hero checks, Villian bets, BB folds, Hero calls.

Turn (4 BB): 10 [img]/images/graemlins/diamond.gif[/img]

Hero checks, CO bets, Hero calls

River (6 BB): 4 [img]/images/graemlins/diamond.gif[/img]

Hero bets, CO calls.

Too loose by Hero, or just right? If you agree with this line, does it change if BB calls the flop bet by Villian?

(And I was wrong on the 8,8 hand posted earlier this week. Thanks for all the posters who reasoned out why the call was correct. Your thought processes were extremely helpful).