I don't know, it is unacceptable to withdraw from your card.  However try to mail them and ask. As I know in order to verify paypal they withdraw around 2.50$ from you card and then when you verify they put this withdrawn  amount in your account. Probably they do something like that, don't know because there was nothing like that in my account probably because i bought contract with card. Ask them, it is up to 3$ and if they put this back to your account, then doesn't seems problem.