Jacking people at the pump is not econ 101. There is a greater demand for gasoline and a higher price, therefore they're switching production of diesel over to gasoline. Market clearing of gasoline is growing in quantity, and stablizing price (if things like this didn't happen gas would be much more expensive).
Demand for diesel is the same, now supply has decreased (shifted left) -> market clearing price will rise.
That's Econ 101.