Live 1-2, KK played too weakly?

[deadmoney98]

Live 1-2 at Caesar's AC, Hero has ~350, Villain covers.
Villain is a good, aggressive, thinking player (a rarity in this game). He will raise basically any two, but generally has reasonable standards for calling a raise and has shown down the goods in all his big hands. My image is TAG, bordering on rockish. Anyway, the hand...

Pre-Flop
Hero is on the button with KK.
Villain limps either UTG or UTG+1
2 or 3 players limp behind
Hero raises to 15
Villain calls, MP limper calls.

FLOP Q 3 4 rainbow
Villain leads for 35, MP folds, Hero flat calls

Turn 8
Villain checks, Hero checks

River J (no flush possible)
Villain bets 25, Hero calls.

Comments on all streets appreciated, rationale and results to come.

FWIW, I had seen villain check top pair on several occasions, but he did lead out one time with TP+OESD in a multi-way pot. Also, MP was a really bad calling station and not much of a concern to either one of us I am sure.