I just checked mine ... 1337 days seems like a good number :)
Secondly, I know your comment was tongue-in-cheek, but that would actually be a very appropriate age cut-off for what strikes me as a remarkably elitist endeavor.
TBH I'm fascinated to know how the community would differ from HN of 4 years ago, since all the older participants would be 4 years more experienced in life and hacking.