Plaster in engine?!

Well, after a day of riding and then cleaning the bike, I decide to take off the plastic cover on the left side of the engine which is over the magneto and stuff. I haven't taken off this cover in a month or so, but when I do after riding many times that month, a few teaspoons of pre-mix gasoline drips out. But when I took the cover off this time, about a tablespoon of what looks and feels like plaster came out :think: . It had that greyish tint to it and was real mucky. I assume that this is the pre-mix and maybe some water that leaked past the gasket, but not sure. Anyone know what this is for sure, or any thoughts?
Thanks alot
Jim

I know that the crank seal has a leak in it, its not that bad though. I was just wondering how it turned greyish and plaster like, it never had before. Thanks alot for the replys.
Jim