I have heard similar things from my bosses, who are both on the admission committee. Basically, they insist that the application deadline really only applies rigorously to the applicant. Just make sure the recommendation arrives before the admission committee gets together (early-mid Jan typically?), or a week or so prior to this date so an administrator will have time to compile everything together.
I am in the same position right now, and it's a little unnerving to have the recommenders taking their time days after the deadline has passed!