Was "Mazda" just a service writer at a dealership? I don't believe the answer. Nothing in the owner's manual nor anywhere else tells us the minimum proper driving time or distance. My 2016 engine's oil never smells of gasoline. I suspect that you have a leaking injector. The fix will be for the dealer, under warranty, to replace all the injectors; that's easier than testing and finding just the one leaker. Go back and talk to the service manager, not just one of the service writers. Phone ahead for an appointment with the service manager if that works best. Also phone the real "Mazda," Mazda North American Operations, (800) 222-5500, before you see the service manager. Ask if significant gasoline in the engine oil is a serious problem. They'll always refer you to the dealership, so inquire what you should ask of the service manager.