Your credit card info was not passed along by iTunes so if you suspect that it has been compromised, contact your CC provider and immediately cancel the card. Place a stop payment on charges until you get it sorted out.

I have had my credit card info stolen at a popular department store and was not aware until a charge appeared that I did not make. The CC company stopped payment and reissued a new card to me after canceling the old one.

Don't take chances with your credit. If you even suspect that there is a possibility of someone having access to your CC, cancel the current card and ask for another.

Regards.