Sorry for not getting back to this sooner. We did some testing initially when you reported the issue, but couldn't recreate it then. We also haven't heard of this issue from any other users.
Finally, I just tested on our demo site and it seems to work just fine there. The demo site has full admin access, so you can check how we've configured things. Can you try registering on our demo site, or checking out the configuration there to see how it differs from yours?
demo.sourcecoast.com/
There's no reason that functionality should have changed based on changes from Facebook or from JFBConnect. It sounds like there may be something on your end that could be altering the birthdates as they are being imported, but I don't know your site or configuration, or any recent changes you have made, which may be causing this.
Hope that helps get you started. If you can recreate the problem on our demo site, definitely let us know as that will help narrow down possibilities.
Thanks,
Alex