Unaging and Age Quickly - Double Your Fun?

Does it make any sense (both in terms of rules and in terms of story) for a character to have the Unaging Virtue and the Age Quickly Flaw? As in, the character builds up decrepitude quickly, but shows no external effects until crisis?

I don't see any problems either from a rules or story perspective.

It seems like an interesting combination.

And Devil Children inherently have both already.