Take a look at your fridge access panel on the side of your motorhome. In some cases water can all run down the side of the RV and make its way in through this panel. Depending on how the drain holes work behind the fridge (sometimes there are none!) you can end up having water pass by the holes and end up making it into the RV and onto the floor. Folks solve this by making a dam out of a caulking in the area behind the fridge that forces the water away from the other susceptible areas.
Don't think this happens? It does, depending on the design of the rig. Attached are some images from a different RV forum that might be of help for you if this happens to be the problem in your situation.
History: '08 View, '05 Chinook, '01 Jamboree 24D, '78 Apache Popup, 81 Komfort Tlr,
84 Mazda B2000 'w canopy,
Tent from wedding shower in '96