Not a stupid question at all. If you mist during molting you risk disturbing them and having them fall. I wouldn't mist during molt. If you mist them as needed on a regular basis they should have all the moisture they need to molt successfully.
If you mist away from the mantid down the side of the cup its fine,but if its a species that doesn't need a lot of humidity or coolness then don't worry about it as said,just let it be unless it needs some saving later on