This is normal. Not normal that no one told you about it, but is part of the process. Fortunate for me I knew about this process prior and had the bunk ends open during a really good rainy day or couple days actually in my driveway. Normally you can water using your garden hose but during this time, the seams will leak. But after a good watering, it will seal as it dries and then you're fine. Sometimes a second watering is necessary to get the missed spots.
Sorry your experience was bad here. It sucks when the dealers don't take pride in their work.
"Take The Road Less Traveled"
2013 Rockwood Roo 233s
2013 Ford F150 FX4
I've been an RVer since 2007, Lifetime Camper