Grease leaking out of bottom of engine

I don't suspect that this is normal, but I have a grayish grease leaking out of the rear of the engine.

I took it for my first ride of the season today and when I had put it away to give it a good look over, I noticed it on the seat tube below the engine. It comes from under the engine, under the chain sprocket for the clutch, and runs down the mounts on down the tube.

It looks like it's been leaking for a while.................I know what you're going to say, "Don't you look over it more often?" Well, I guess not.

It runs good and everything seems "normal", but I just want to know if this is something I can just write off.

I guess silence on this issue means everything is peachy and I can just write it off as a normal occurrence.

Cool, it's another nice day for a ride!