it's very common with new owners who close everything up when it's cold.
an RV is not like a house, that you have to button everything up, like a submarine.
you need to allow for air movement. crack a window and vent so that air can move.
with a propane furnace and humans breathing out moist air, condensation will form if air can't move.
and Zoe the Wonder Dog(R.I.P.)
'07 Roo 23SS pushing an '07 Chevy Avalanche
Equalizer WDH and Prodigy BC