These type of threads appear with embarrassing regularity. Virginity is something personal - to some people it doesn't mean anything, to others it's everything, and then there's a whole spectrum in between.
I suppose what I'm trying to say, in the nicest possible way, is who cares? If you want to wait until marriage, that's your personal choice and how other people react to that is up to them. Posting yet another thread on TSR won't suddenly solve the question of how old is too old, mainly because it's not a question that you should be concerned with.
There probably are situations where if someone revealed they were a virgin and they were past a certain age, it might seem odd, but that's really no one's business but their own.
I'm not quite sure what I'm trying to say here - I suppose I'm just ranting about the obsession with this topic on TSR!