You're fine, tires that are not directional all have the same tread pattern so one side will always look like they're spinning the wrong way. Look at some wheels, same thing, one side will look like they're spinning the wrong way since they're not specific to one side. Also, after a rotation tires are always a bit louder, that's why you rotate them so they wear evenly. They'll quiet down until you rotate them again.
2014 Mustang GT Track Pack
2015 WK2 Limited 4x4