I've heard about this on another forum. This seems to be limited to Chevron stations (on the US west coast?). Apparently it's an anti-fraud measure to prevent someone with a stolen card from using it at the gas pump (The other forum mentioned that this is a place where stolen cards are frequently used because of the ability to purchase without a signature...)
Did the Chevron station have an option to pay inside? Usually you sign for your purchases inside, so there shouldn't be a zip-code check.
For what it's worth, I tried to use a Visa card at a Hess station in North Carolina twice in succession (my car takes 91 octane and the pump had sold 89 and 93, so I wanted to "blend my own") and an anti-fraud lock kicked in on the second swipe.
PDH
[This message has been edited by pdhenry (edited 09-08-2002).]