My guess is there is a feature to expire passwords and it was turned off, so in order to force everyone they turned it on, then just set everyone's password date to an arbitrary value that made sense, and then everyone was shown to be the same age. Mine was shown to be that number too and I had just changed it. Could be there is no feature to force it, so that was probably the best thing they could do.
It seems a lot of forums are starting to take more measures like forcing expiring passwords. I typically reuse the same password on all forums, but given it's not something I have to login to all the time as I use the remember password feature, think I'm going to start using a different randomly generated password on each forum/similar service now. Seems way too many sites are being hacked now.
I don't even remember the last time I changed my FB password, I should maybe do that some time. (no, it's not the same as AT. )