Gas Stations Informative - Gas Station Bait & Switch
I just saw a clip on ABC News. There are some gas stations charging extra for using a credit or debit card without posting a notice. In all states if there is a price difference between cash and credit the difference must be posted. One station was caught charging 50 cents extra (per gallon!) for card use.
So read your receipt, if they charged more than the posted price complain immediately.