Interesting hand vs Harrington

[shaniac]

I regret not doing one thing in this hand:

First orbit in the 5K NLHE some weeks back. Harrington is in the 6 seat, I'm in the 8 seat and we have same-sized stacks.

Harrington opens the pot in EP (maybe UTG) for standard raise in level 1 (probably 150 to go) and I call with AKo.

Flop is A53. Harrington check-calls a bet. Turn is an ace. Check/check. River is a 4 for a final board of AA345. Harrington checks, I bet ~500 (iirc) and now Harrington check-raises me to about 1500.

I call.

I think I made 1 mistake during the hand. What do u think?

Shane