Take it to the dealer ASAP and expect it to be under warrantee.

What he said. As a 2010 it should be covered under the 5/100 powertrain warranty or if somehow emissions related covered by the government mandated 80K mile emissions warranty. His base 3/36 should still be in effect (or almost over) unless he drives the piss out of the car.

Don't screw around with a strong gasoline smell.

I will agree that on a cold start on a cold morning a faint smell for a few seconds is possible, and would be normal.

Also agree that I don't see this as a fuel injector issue. As those are monitored by the OBDII it would almost certainly throw a CEL.

The 2007 to 2009 Chevrolet Cobalt was recalled in southern states for a plastic part on the fuel pump that could crack and allow fuel to leak. I would speculate this was addressed in the 2010 model year - but worth noting the known issue on the previous year.