http://www.usatoday.com/story/news/nation/2013/12/18/secret-service-target-data-breach/4119337/
I haven't used my card there in months, but this week my number was stolen and they tried to use it in the UK. I'm suspicious that this was the source, since they store your data for a very long time. Check your statements if you shop there, and be very cautious if you ever paid with a debit and PIN.