I do not think you would have any problem with people trying to scan any information off the card that can be used to make fraudulent credit card charges.  If you want to be secure, you can buy sleeves that you can put your cards into as well as sleeves for passports.   Over a year ago I was coming back into US at Peace Gardens and agent told me that at that time if it would have been working properly, he could have seen who was in the vehicle by rfid reading of tags on passports/passcards in the vehicle. 
To test the sleeve theory I was going to try to see how well a sleeve could block the rfid card reader at my local elevator.  I keep the card on my dash of the truck and can be read as I drive up, I was going to sleeve it and see how well is can be scanned.