I've never had it happen to me, but if you're getting small bogus periodic charges, that generally means your card number has been stolen. It's how thieves try to milk you without detection.
Was this a card you used for online purchases?
Favorite ERF quote: "I'm not going to waste my time on someone who's more interested in being stubborn or obtuse or intolerant." -- Nords
Favorite ERF error message: "Sorry Nords is a moderator/admin and you are not allowed to ignore him or her."