Looking at Charlotte area stations on
GasBuddy.com - Find Low Gas Prices in the USA and Canada it looks like all the Shell stations raised it up to $4.29 and neighboring stations followed suit. However, there are still plenty of Exxon, Texaco and Hess stations at $3.65 or less (for now).
Upon further review it looks like suburban stations are around the $4.29 mark, but it's cheaper the closer you get to downtown.