After I got back from my weekend trip, one of the girls was quite helpful and assisted me in laying out and photographing my various loots. She then brought my razors into my shop, and took one of the stones I picked up and washed it, as it was quite grimy and left a rather thick blackish residue on hands. Well, this morning I saw that it had developed... growths on it. She says she just used warm water, no soap. Any ideas? Is this bad for the stone? Should I go soak it in oil for a while?