The case of the disappearing gas leak

This story is a bit of a mystery. We were winterizing our 2005 Jayco Granite Ridge when I noticed a small puddle underneath the middle of the RV on the driver's side. There were two small drips coming from a bracket that were leaking gas. I can't tell what's above the brackets. I put a bucket underneath to catch the gas and had between pint and a quart the next morning. So I took it that morning to the garage and just like that- it stopped leaking. THe mechanics parked it on hills, drove it, ran the generator- and no leak. They put more gas in it, until the tank was full- and still no leak.
It seems weird that a leak would stop on its own, and the garage recreated various possible scenarios that might cause it to leak. Any ideas or suggestions? Has anyone else ever had a similar experience?