It doesn't necessarily have to be an online site where your card info gets stolen. Could be a gas station, restaurant, or retail store. I had mine stolen one time while driving through Massachusetts -- had to be either the motel, restaurant or gas station we used during an overnight stay.
Welcome, Colin and Jonathan. As you can see from the responses so far, this is a tight knit online community with quite a few long time members. Personally, it's my favorite Internet site. I look forward to your future contributions.