Dude, you are 15! You don't need to be stressing yourself out over a girl 2 hours away. I would let her go, take a deep breath and feel the relief of the situation no longer existing and find a girl local to you and enjoy your life man. If I had known at 15 what I know now 30 years later, life would have been a lot easier then and much more fun.
And yes, at her age I would be worried because she doesn't have a clue about love or relationships either. If she has an ex that is acting like an idiot and she hasn't told him to get lost, there are issues there.
Not trying to be harsh, but just giving you my opinion after quite a few years on this earth with quite a few relationships under my belt.