rear brakes get too hot
27 miles on the highway can generate a lot of heat from multiple places.
The rear gears and bearings tires and brake drums all generate heat just under normal running conditions.
Try checking the entire rear end when you pull in from the drive.
(Is it by chance uniformly hot from tire to tire?)
Also, "to hot to touch" isn't that hot for brakes at all so this could be a normal condition since we can't feel it.