This is the time of year that the refineries start changing over to the 52 different "blends" as required by the various state mandates. As a result, more changeovers means more downtime which results in a loss of economies of scale.

Also, don't forget that NC has the highest state gas tax at 29.95 cents/gal.

Here's the other SE states per gallon:
WV: 27 cents
VA: 18.1 cents
KY: 21 cents
TN: 21.4 cents (and no State income tax!!)
SC: 16.75 cents
AL: 18 cents