Many of the gasoline stations along I95 on that corridor say on the pumps "May include up to 10% ethanol".
My take is that some stations may have a smaller percentage of ethanol, perhaps the Virginia stations have a smaller percentage. One of my fill-ups on my last run was in Virginia, a shell station right off a northbound exit in the 20's, an isolated stretch. If I got better mileage, I didn't notice.