Recently on a short camping trip we had to leave the campground before light. It had just started to mist a bit but I didnt think much of it. Well when we got home the next day I opened up the camper and the "mist" had turned into quite a bit of water. I dont know if it was condensation or not but some of it ended up on the inside of the trailer. I was very glad it had not gone long and I didnt just take it to storage. It was no where near 3-4 gallons and it was not in there long.
If your dealer had left that closed up for long it likely could have leaked into the camper and caused some damage. I would look very closely before buying maybe even consider looking elsewhere....
good luck with your purchase.
Ryan