I rode I-10 between Jax and Louisiana on 29 Feb 20 and saw a range of fuel costs for regular, from $2.05 to $2.59. Nothing really out of line with what I was expecting, though I didn't stop at any Shell stations. Here in Florida, we have some of the highest fuel taxes in the country, plus add in the local sales tax. Sometimes the gas station doesn't really have discretion in their gas prices, it's dictated by the brand they sell.
I didn't stop in Chipley, FL but I did stop on either side of it - Marianna on the way out and Defuniak Springs on the way home. I saw a $0.32 difference between the two. They're in different counties so that may explain the difference, or at least part of it. Looking online, it appears that Washington county which is where Chipley is located, has pretty high prices throughout the county.
I don't know about that particular Shell you stopped at, but those in our local area tend to be higher than others and I'm guessing it's due to brand dictate.
Not that any of this helps with your high fuel prices in Chipley, FL, but it may help explain why you saw higher prices there.