That would be a realistic change...it would be a cool way to tell your characters story, starting out on their journey as a young adventurer and ending as an aged battle worn grey mane
Oh, I meant like in one barber trip.
Ex: You went into a barber shop and said "I requireth a fulleth beardeth" <-- Nordic talk

. I agree that it would be cool if you grew facial hair over time though.
I guess some people can just pretend years have gone by, but I can't really do that.