I have a CS Recon Scout that has lived in a Kydex sheath for over ten years without a problem, but then I leave my Randall No 8 in its leather sheath most of the time too, and it has never had a problem either. But I use the Randall a lot, removing it from the sheath daily. I think the main problem would be moisture on the blade or in the sheath (the Kydex one)...might be a good idea to borrow the wifes hair dryer and blow out the sheath before storage.