Unlimited arrows?

I'm using the ranger bow from the DLC and any time i enter a safe zone i get a full stock of regular arrows. i started a new game and after the initial volatile chase, i got back to the tower. i could then step outside, shoot a couple arrows at a volatile, then step back in the boundaries of the safe zone. Whenever i exited again, I'd have 60 arrows. is this a bug or is it normal?