Yes. What you have is condensation. When its warm inside and cool outside you can get condensation on the canvas (and the windows too). A few things to help that:
-Air flow - Crack the canvas a little at both ends and crack one of the roof vents. Air flowing along the canvas will reduce condensation.
-Turn the heat down and use the heated mattresses. We usually keep the furnace at 62 at night.
-Popup Gizmos or a home-made version. These will help with condensation in cool weather and reflect the sun in hot weather.
Try to reduce the condensation so its not dripping on you, but otherwise just wipe the canvas off in the morning or let the sun dry it out.