It's a market thing.
Diesel is primarily serving commercial operators. They have to buy X gallons per week regardless of the price. Efficiency is always important. Even with low fuel prices, fuel is still a major cost of business. The result is diesel prices tend to be inelastic. That means they tend to be slower to go up and down.
Gasoline is primarily used by private individuals. Particularly when fuel prices are low, they tend to be less focused on efficiency, so when prices rise, they have more ability to reduce consumption. It could be as simple as easing off the throttle. It could be taking the compact car instead of the big truck. It could be skipping an optional trip. With a major price spike like we just went thru, it's not hard for a typical family to cut 10-30% off their gasoline consumption. The result is gasoline prices tend to be more elastic and thus go up and down faster as they try to react to the changes in demand.