Stop in for a cup of coffee

OK here is something about price gouging I always wondered about say you have a gas station and had a full tank of gas in the ground and the price goes up just for ease say $1 a gallon, so you are able to jack up the gas you bought for less by that amount even though you paid yesterdays price for it? Just to me seems unfair. But if joe across the street got a delivery 1 more and added extra .5 to it so it is say 1.50 thats price gouging!