GAS PRICES

A couple of weeks ago a man was explaining why gas prices go up immediately when the price of a barrel of oil goes up. His reasoning was that the gas stations know they will have to pay more for their next shipment. My question is why the reverse doesn’t apply? Doesn’t this mean that the next shipment will cost less? Gas has dropped almost 12 dollars a barrel. The price has come down ten cents. It seems the logic of this is way off. Let’s attribute it to greed.