I've had 3 incidents with my USAA MC over the years.
1) I got a call asking if I had made any purchases of pet food in Paris, France. I said no. I was asked if I had my card in my possession. Yes, I said. Operator said, hold for a second while I cancel your card. I heard a keyclick, then the operator said "Your new card will get to you within 48 hours".
Fast forward about 2 years:
2) I got a call asking if I had made a purchase from an Apple store in San Francisco (I live just outside KC). No, I said. Again, the same keyclick, and a new card came in the mail a couple days later.
Fast forward about 3 days:
3) I had my new card, and was trying to make a purchase. I had already activated it, but apparently, since this was the first purchase on the card, the cashier had to call USAA to get it 'really' activated. Problem was, "their computers were down" and they couldn't process it for another hour. That kind of sucked, but it all worked out.
Never had any problem with buying fuel at different FBOs in different cities on the same day, but they do flag odd things pretty well.
I've used USAA for the last 30 years for car and home insurance, college savings, credit cards, ..., they are always great to talk to - you really will get someone in San Antonio, and not in any of the 'stans.