Were you opening a top vent and a lower window? This will create a very small undetectable draft and will pull the moisture out. They don't have to be cracked much, just about a 1/4" for a pass through window and 1/2 turn on the roof vent.
Also, if you plan on camping much in cold weather and don't have thermo pane windows, use 1/2" foam board in the wondows you don't care seeing through and 1/16" acrylic for the ones you do. Easy to cut and file for a snug fit. I just use blue painters tape to hold the acrylic in while the foam board is cut snug enough to stay in place.
With the foam, acrylic windows, and venting I don't have any problems down to about 0* with two people. If I notice some condensation trying to build up, I just open the window and/or vent a little more. When cooking I open up the window behind the stove and crank the roof vent another turn or two to remove the extra moisture, though the colder it is, the more I stay away from the high moisture cooking like boiling things.