A few points. From my Econ 101 days, all other things being equal, prices for goods tend to be “sticky” on the downside, especially if it’s a necessary good. Margins on gas tend to be thin due to competition and the fact that there are only so many refineries or distribution hubs in a given geographical area. So unless the station owner wants to use gas as a loss-leader for a convenience store, which some do from time to time, it has to immediately raise the price. Seeing a tanker arrive at a station at a time when gas prices are rising is usually not a good omen. On the other hand, if crude prices are falling but people are still filling their tanks, why drop it? And if demand is there, why not raise it? So there tends to be about a two or three-week lag between a drop in the price of crude and fuel prices.
Another consideration is crude oil only comprises about 40% of the cost of gasoline. There are other factors that affect the price, such as the cost of transportation. If those are high or rising, they will tend to retard any drop in the price of fuel or possibly be passed on to consumers in the form of higher prices.
Finally, gasoline is traded on the commodities futures markets just like crude oil. While there tends to be a correlation between the two, that’s not always the case.