This morning I logged onto my internet banking account and looked over the various entries there. Much to my surprise, there was a large authorized (but not yet posted) charge for over $1000 from a major retailer from whom I had bought nothing in the past month or two.
I called the credit card company and within a very short time my card was blocked, and a new card sent to me; I'll receive it in a few days. Also I will not be charged for that transaction since it appears to have been a fraudulent use of my card.
Apparently the card had been used to do an address check with another retailer a day or two earlier where nothing was purchased.
The security person with whom I spoke said that there is no way to tell when my card may have been compromised. I guess it's time to start carrying tinfoil in the credit card section of my wallet? Or maybe just buy a new wallet with RFID protection.