The opponents were willing to play in 3♠ Doubled which is quite a different thing than being willing to play in 3♠. From what I've seen I think most times the opponents would bid 4♠ to make on hands that they would likely make 4♠ the first round as to give us less time to find a profitable sac or makable game ourselves, or to nail us if we bid wrongly on the 5 level. Since everyone here seems to agree that pass is non-forcing however, then I still pass - your hand is missing too many aces to make the 5 lvl likely to make, especially with the fact that the heart honors the opps have are likely to be over partner's honors. The scoring also makes a vulnerable game not as attractive at MPs.