Mine had the same problem. First dealer found nothing, and the problem happend again. I called crossroads and let me go to another dealer who did a water test and found the seals around my big slide were not done correctly. MAKE SURE THEY DO A WATER TEST. Some dealers try to get out of this (ie the first one). Good luck.
2008 F350 Super Duty 6.4
2014 Sunset Trail 32bh
"I work so I can CAMP, I camp to get away from WORK"