Leaving out the FBO's at Jet focused airports, it's a cash business. With prices going up dramatically, the next load they buy is going to cost a lot more. They have to pay the supplier up front, then wait for the fuel to sell to recover that higher cost. However, employees still need to be paid, utilities etc. So yes, if I ran an FBO, I'd raise prices on part of a fuel load that I bought at a below current market price if I expected the next load to be at a significantly higher price.
The ability to do that is not infinite however, there's a point at which either pilots stop flying or they tanker from another airport with a lower price.
The exception is the Class B and some C airports near large cities who get so much jet business, they don't care about piston and price accordingly. Still a market driven price and while I don't like it, I also don't buy from them unless I have a very compelling reason to be there.