Gas smell

I recently just bought a used 2004 A6 Quartro S-line 2.7T.  I'm very pleased with the car so far???  Anyway, I'm getting a gasoline smell in the cabin and rear of car, especially in the back.  Anyway my CEL came on and I had it scanned.  All it said was the fuel cap.  My cap is on and appears to be fine.  Could this really be the problem, or is it another issue that set off that sensor?
 
Thanks KK
 
 

Is the code P0455? If so, make sure the cap is
on tight. If the problem still occurs, replace the
gas cap.