Did my opponent "outplay" me?

[hemstock]

Villain is TAG and seems like a good and thinking player.

PokerStars 0.25/0.50 Hold'em (9 handed) converter

Preflop: Hero is UTG with K[img]/images/graemlins/club.gif[/img], K[img]/images/graemlins/spade.gif[/img].
<font color="#CC3333">Hero raises</font>, UTG+1 calls, <font color="#666666">6 folds</font>, BB calls.

Flop: (6.40 SB) 5[img]/images/graemlins/spade.gif[/img], 7[img]/images/graemlins/heart.gif[/img], A[img]/images/graemlins/spade.gif[/img] <font color="#0000FF">(3 players)</font>
<font color="#CC3333">BB bets</font>, <font color="#CC3333">Hero raises</font>, UTG+1 calls, BB calls.

Turn: (6.20 BB) K[img]/images/graemlins/diamond.gif[/img] <font color="#0000FF">(3 players)</font>
BB checks, <font color="#CC3333">Hero bets</font>, UTG+1 calls, BB folds.

River: (8.20 BB) 4[img]/images/graemlins/diamond.gif[/img] <font color="#0000FF">(2 players)</font>
<font color="#CC3333">Hero bets</font>, <font color="#CC3333">UTG+1 raises</font>, <font color="#CC3333">Hero 3-bets</font>, <font color="#CC3333">UTG+1 caps</font>, Hero calls.

Final Pot: 16.20 BB

Results in white below: <font color="#FFFFFF">
Hero has Kc Ks (three of a kind, kings).
UTG+1 has Ad Ah (three of a kind, aces).
Outcome: UTG+1 wins 16.20 BB. </font>

I immidiatley go like
Hey man, that's how you play your aces? That's really dumb.
Did he outplay me? He played it really sneaky and got the best out of it. Theoritically, it's not a good think not to raise your aces. But in this particular hand, did he played me? Was I the dumb one in the hand?