I`m afraid I`m with the other guys - call.
It`s easy to say after the event when u know what has happened, but all I would say is that if he had hit a set I don`t think he would have gone all in. If he had limped I would then have been worried.
I would be interested to know how long it took you to fold.
Did u think it through?
Did u go by gut feeling only?
I would have called his all in and, looking at the flop, expected to see 6,7/ spade, spade/ or a pair less than mine.
However, not being to clever about it, if he had turned either A8/ K8 I would have not been suprised.
As I said before, him turning a set is unlikely, unless he is a very poor player and is affraid of the flush draw.