maybe bad... condensation usually is related to the humidity... if the tank is at the right temp probably not a bad thing... ive been told though LOW TEMP + humidity = Bad... if the temps are right then dont worry... IMO. i;d keep an eye on the night time temps and make sure they dont get too cold ( it sounds like it does). also check for snake poo... when mine drop a deuce it normally fogs the windows on the tank...
Yeah, it's fine in a frog enclosure. It happens to mine all the time. When a room is cold and the enclosure has a heater keeping water warm it causes condensation to build up on the glass. Usually most cold morning mines all fogged up and as the room warms up over the day it slowly disappears.