Accidentally folding the nut flush

[Nichlemn]

I can't get the hand history for this (which would be nice so I could be assured that it actually happened like it did), but it went roughly like this:

NLHE, limped multiway pot. I have A[img]/images/graemlins/heart.gif[/img]5[img]/images/graemlins/heart.gif[/img].
Flop comes A high with two hearts. Checked around, I bet, someone calls (I think I'm in position).
Turn comes another A. I bet again, call.
River comes the third heart. The person bets. I think for a little bit and fold, thinking I'm at best a split versus Ace rag, and losing to a higher Ace or a flush.

However, I somehow manage to completely miss the fact I have the nut flush. I'm not the sort of person to misread my hand - I don't think I've ever not noticed having a hand before. I clearly noticed the suits given that I was betting my TP + flush draw, and was concerned about flush board on the river. But a flush of my own does not occur to me, and I end up folding to someone who very likely had a lower flush or trips.

I think it's to do with turning trips. It shifted my focus entirely to the made hand, allowing me to sit there on the river with three hearts on the board and two in hand and still thinking all I had was trips. The fact that having trips and a flush at the same time is unusual in Hold'em may have contributed. Also the fact I was betting and my opponent was calling may have subconciously made me think that only I had a made hand and my opponent had a draw.

Any thoughts?