average live of a headliner is 8-10 years, depending on a lot of different things. the edges that get a lot of sun exposure will be the first to start going.
i recovered the a-pillars in my wife's car 4 years ago, and they are needing to be done again. i'm sure the material i used was sitting around the shop for a couple years (a light blue that barely gets used) so that didn't help any.
if you can deal with it for now, toss a couple staples in it. they won't be very noticeable up on the front edge. then when time/money/etc is right, get it redone.