Has anyone ever experienced an intermittent fuel leak in an early car?

I started her on Monday and backed out of the garage. When I looked back I saw a puddle. I left the car idling in the driveway to check out the garage. It was in the rear left and smelled like fuel. When I got back to the car, it was leaking there too. I pulled back in and had the car flatbedded to my shop on Tuesday.

Since then, they have had it three days and have yet to find anything wrong. Nothing at night, nothing on start, nothing during or after driving. They checked the lines and said they look new when the motor was rebuilt 2,000 miles ago. The pump was dry and had no evidence of a leak.

I am stumped as to what this could be. I am about to get the car ready for her winter slumber and don’t want to put her away with any issues. Any ideas?