Auto parts stores can be iffy when clearing the codes, some will and some won't. Another option is to buy your own OBD II/CAN tool and clear the code yourself. I bought one for around $100 and have found it useful in both of my cars.
2014 Grabber Blue Mustang GT Premium with nav, RR and comfy packages, 3.73 limited slip axle and optional 19" machined aluminum wheels. Come hang out in the garage and check out my build so far!