whilst waiting for the Stt's on vc to fill up this morning (usually takes ages) i decided to play a bit of cash, so i sat down on a 6 seater and 9seater 2/4nl and a 9 seater 1/2nl with $300, $300 and $200 respectively. A strange hand takes place on the 1/2nl table after onlya few hands, which led to a lot of discussion afterwards.
I am in on the button and there are 3 limpers I have

can call the $2 the small blind makes it up but the BB raises to $6 which everybody calls.
Flop---------

i think beautiful and proceed to check

as do the other 3 in the hand, the turn brings the ks which makes my flush and i decide to bet $12 into a $26 pot which gets one caller, obviously at this point i think he has a high spade. You can tell my delight when the

hit the river and the caller is first to act! he bets $20 into the now $48 pot. Great i think he has the asp and he can double me up, so i decide to raise to $100 leaving myself $30 expecting a call at the worst. He then dwells and passes! and then claimed to have the Ace of Spades after id shown my str8 flush.
If i were him i wouldve found it verydifficult to pass the nut flush here for another $80 (he had $350) in his stack, especially if he called the turn bet to catch a spade on the river!
or
What do you guys think, my after thoughts were that he was either representing the or more logically had the qs
and would anyone on here pass the asp in his position the way the betting went?