One night, when I was with some friends, umm, "recreating," I discovered that my (at the time) favorite tobacco was horribly, horribly overdry. Unfortunately, I had already been "recreating" for several hours, and ended up just turning on the sink to a very low level and putting some water straight into the tin. And then stirred it all around with my finger. When I came around the next day I vaguely remembered pouring water into my Vanilla Cream tobacco. I hoped that it was some sort of false memory; but no.
Luckily for me, I had left the tin's top off overnight, and it dried enough that I didn't have to worry about mold.
Moral of the story: never rehydrate tobacco whilst "recreating." Ha ha.