Weird Gasoline Leak Today. Thoughts on Cause and Source Appreciated

I was working on a friend’s RV today, so I parked the Barracuda Way down at the bottom of the driveway to keep it out of the way and keep it accessible. When I went to pull it into the garage, I smelled the strong smell of gas. There was a good puddle behind the car, and more gas was dribbling out from the left side. I had just filled it up yesterday. It was much warmer today
01.JPG

My first thought was that the donut gasket where the filler tube goes into the tank had sprung a leak. I looked underneath the left side, and the donut gasket area was dry.

02.JPG

However, gas was dribbling out through the two rear-most holes in the left frame rail. I thought, “What could possibly cause that?” I was afraid that the warm weather and the full tank might have resulted in the fuel expanding enough to somehow get into the trunk.

03.JPG

And OF COURSE the trunk lock picked today to break, so I drilled it out and used a screw driver. Trunk was dry. The leak stopped, and no more since. What the heck??? Any ideas wher the leak came from??

04.JPG