Laying down KK?

I can't help but think that my last month of bad runs "helped" me lay this monster pot down. How can I call an all in shove from a RR'ed Button who is a 16/15/0.3 (121 hands) player. He's tight PF, weak post flop, clearly. I was afraid of the 3bet button from the start and told myself I would play it very safe. In fact, I even CONSIDERED laying down pre-flop. WTF? These are some TERRIBLE players.

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

UTG+1 ($1.88)
MP1 ($16.72)
MP2 ($1.40)
CO ($4)
Button ($11.95)
SB ($10.36)
Hero (BB) ($16.81)
UTG ($2.13)

Preflop: Hero is BB with Kh, Kd
3 folds, MP2 bets $0.40, CO calls $0.30, Button raises to $1.60, 1 fold, Hero calls $1.50, MP2 calls $1 (All-In), CO calls $1.20

Flop: ($6.25) 7d, 6s, 9c (4 players, 1 all-in)
Hero checks, CO bets $2.40 (All-In), Button raises to $10.35 (All-In), Hero folds
Very dangerous board; the button shove says clearly AA and all the actions prior says sets, straights, etc.
Turn: ($11.05) 4s (3 players, 3 all-in)

River: ($11.05) 10h (3 players, 3 all-in)

Total pot: $11.05 | Rake: $0.73

Results:
Button had Kc, Ac (high card, Ace).
MP2 had Jd, Js (one pair, Jacks).
CO had Ad, 10s (one pair, tens).
Outcome: MP2 won $5.28, CO won $5.04
Very surprising play. Terrible laydown by me. WTF, though? Terrible play by the rest of the players; worked on me, though.