Smelling gas outside the car, but no obvious leak?

What is your question?

I don't see any leaks in the driveway, but there's a faint smell of fuel as I walk about the rear of the car. The fuel cap is secure. I thought it was my neighbor's old truck, but now I'm pretty sure it's my car.

How long has your 2010 Mercedes-Benz GLK350 had this problem?

a couple of weeks.