Hey TPE, first time poster. 

game is a .05/.10 cash game, 5 handed at the time.  UTG+1 is the main villain, and I have played agaisnt him before.  He is very loose, and has stacked off against me with top pair once, and has made other horrendously bad plays effectively shoveling money at my face.  I am specifically trying to play pots against him, preferably in position.

sb 12.07

bb 9.02

UTG 3.61

UTG+1 (Main villain) 19.93

BU HERO 12.6

I’m on the BU with K8 of diamonds.  UTG and UTG+1 both limp for .1.  Getting good pod odds in position, I limp, the sb completes and the BB checks.

Flop:  2d5c5s  Everyone checks.  I am planning to give up

Turn: Ad  giving me a nut flush draw.  

bb min bets .1, villain calls, I call.   sb folds, and UTG folds.  I think my call here is -EV in a vacuum, but I think if I hit my flush and villain has a hand, he is likely to pay me off, so I’m comfortable calling the min bet here.  If a K comes on the river, I am very likely ahead as well.

River: Td  giving me the nut flush. On a final board of 2d5c5sAdTd

bb min bets .1, and villain shoves over him for 12.4 effective into a pot of .7.  Very unexpected bet size, but my history with villain makes me think he could be doing this with any myriad of bad hands.  He has been so passive in the hand up until now, its hard for me to see him showing up here with something other than a flush.  I wouldn’t be *that* surprised to see him shove AT considering other plays he’s made, but I think 76d, 87d, 98d, QJd, maybe 34d.  Vaguely possible he is doing it with a random 5, but I wouldn’t expect it.  Possibly a hand like AK or AQ trying to bluff a weak flush off his hand.

I call with the nut flush and he turns over AA for Aces full and I am utterly flaberghasted that he played it this way.  Limping pre, checking the flop, then only calling a min bet on the flop.  Basically my hand is the only possible thing that could conceivably pay him off.

Did I make a particularly big mistake calling his shove, or is it reasonable to say that I just ran into a cooler when the maniac happened to have a monster and I had a worse monster?