Weak play?

[Charon]

1/2 game, 6 handed.

UTG+1 (extremely aggressive player) calls, button calls, I in the SB call with As6s and BB checks.

Flop 3c 3s 5s

Checked to the button who bets, I check-raise, all call except button.

Turn is the Kd

I check, BB bets, UTG+1 calls as do I.

River is the Ks

I check, BB bets, UTG+1 raises and I fold.

Standard? Fishy?