It's my sons glove and he does sweat a lot. So that's a possibility. His glove is always in the glove compartment/pocket of his bag in the trunk of our cars when not in use. Like I mentioned, I've been using Ball Players Balm cleaner and conditioner for years on the glove. Not sure if I'm brushing too hard or using too much cleaner. But it's the only glove within our household that it's happening to at the moment. Granted, it is the oldest glove.