iTunes stuff always shows up a "APL*ITUNES" on my card, if it is anything other then that, I would say it is fraud. Either way, if that $40 amount is not on your iTunes account then it was not because of what you bought on that account. If you were on WiFi when you signed up, somebody could have grabbed some packets with your CC info.
Dispute the charge and get a new card number, move on with your life. Credit Card issues happen all the time, if something is on your card you didn't put on there, dispute it as quickly as possible, never try to go through WHO made the charge first, just call the Credit Card company, ALWAYS.