This kind of thing is really kind of common,, I often see 20 or more cents per gallon difference from one place to the next,, Heck I have seen five cents from one side of an intersection to the other, both top national brands, why the one had business I do not know.
One thing you find is that counties may have different tax rates, in part based on higher property values in one city or township as opposed to another, and the station in the TAXED area has to charge more than the one in the taxed area.
There are a few other things that affect this too.
So how do you combat....
Visit this URL and / or download the app to your smart phone.
www.gasbuddy.com (App is GasBuddy)
and it will show you the lowest prices in (Web page) Area you select or (APP) distance you adjust around you.
I recall waking up at a flying J one day and checking gas prices.. TWO lowest prices in 3 states (KY, OH, MI) were said J and the Pilot (Same company/price) across the road.