Too tight?

I don't know; maybe I'm a nit. However, I don't understand what MP2 is doing by showing the cards. What is he saying? MP2 is a 30/10/3 - limps a bit too many hands, but otherwise an average player with a big stack.

Full Tilt No-Limit Hold'em, $0.10 BB (8 handed) - Full-Tilt Converter Tool from http://www.flopturnriver.com

MP1 ($20.94)
MP2 ($30.11)
Hero (CO) ($11.43)
Button ($10.39)
SB ($11.38)
BB ($8.95)
UTG ($20)
UTG+1 ($12.05)

Preflop: Hero is CO with Ah, Qd
UTG bets $0.40, 2 folds, MP2 calls $0.40, Hero calls $0.40, 3 folds
I call, in position, with AQo. Not a bad starting hand, though I will pay particular attention to anything off norm.

Flop: ($1.35) 8h, As, 6c (3 players)
UTG bets $0.70, MP2 raises to $3.50, Hero folds, 1 fold
UTG's cbet is pretty standard. MP2 kills it by raising $2.20, almost double the pot. I don't get it. Does he have A8, A6, or 888 or 666? Why is he overbetting into such a dry board? I have to fold because I have NO IDEA where I am in the hand, with .40 vested and UTG to call behind me. I have to believe that even if I had AK, I'd be folding here.

Total pot: $2.75 | Rake: $0.18

Results:
MP2 had Jd, Ac (one pair, Aces).
MP2 showed his cards. Is he saying that he has a primo hand or is he saying "I'm loose; call me & see what I got next time," or is he saying "I had a legitimate hand - see?" Either way, WTF?
Outcome: MP2 won $2.62