The shaft seal is bad, and needs to be replaced. I had it happen to mine a couple of years ago, replaced both bearings and the seal, very easy to do. I have 2GMF. Mine was leaking when the motor was running but it was the exact same spot.
Thanks everybody! I'm sure mine is leaking while it's running also, I just can't hear it. The Yanmar manual doesn't give me much. I assume when I pull it apart it will be fairly self explanatory? Thanks again!