I have this issue with all my hides whenever i use fresh substrate if it isnt dry like aspen. I just wipe it out with a paper towel every couple days and eventually when the substrate dries out a little, the condensation inside the hides will quit forming.
Also there is nothing wrong with it being a little damp inside a hide. My boas used them still and if they didnt want to, they would wander off behind a hide.