I really wouldn't worry too much about if a server is "secure" or not. It doesn't matter. Credit card numbers are kept eternally by most places that accept them.
So have you ever stayed at a hotel, bought an airline ticket, or rented a car? If so, then anyone who works there now, or who ever will can pull up your credit card number on demand until the place goes out of business.
So basically, your credit card numbers are NEVER safe, and are always accessable to near minimum wage employees of places you have used it. So hackers snifffing the numbers are probably the last thing you have to worry about.