If it happened after your oil change.... Are you sure you screwed on the filter and put in the proper amount of oil/removed all old oil?
Well it was professionally done, so it would not be my error if there was a problem. These guys have changed my oil ever since I got the car with out a single problem so I don't think it would be that, however who knows, anyone can make a mistake. He put all 6 qts in and screwed on the filter using the tool to tighten it so I think those bases are covered, as I did watch him perform the change.
2011 V6 Black Mustang Automatic: Magnaflow Competition Series Cat-Back Exhaust, Airaid Cold Air Intake, Raxiom Smoked Projector Headlights, Raxiom Smoked Aero Tail Lights, 93H-R3.1 Bama tune, BBK Long Tube Headers, BBK Catted X Pipe