Does anyone know of a law that makes air and water at gas stations, free to all customers?

As I put .75 cents into the air/water machine at the gas station for air to my tires, a stranger waiting said it was free. That all I had to do was ask the gas station cashier to turn on the compressor. He claims a law was passed a few years ago that makes this possible. That the ability to charge .75 cents is available for after hours service or machines that still stand since installed before the law was passed. Is this law real? Is it a national law or a state law? I live in California.