Smell gas fumes when the car isn't running

What is your question?

After driving around town running errands I noticed that it smells like gas fumes around the passenger's back door really strong and the other side the drivers side not as bad. The fume smell is always around the back doors and back of the car, not so much in the front of the car, also the yellow light is on saying check the back right passenger tire. To me the gas fumes smell like it's flooded impossible I know. And theres no leaking on the ground under the car. Please help, salesman always see me walk in the door. Thank you in advance. Sherry

What makes this problem better or worse?

After its been driven

How long has your 2008 Cadillac CTS had this problem?

Ever since I've had it 1 1/2 years