EDIT: Spoke too soon... it started weeping a little oil on the way home from work tonight.
Just ordered the replacement seal at Ron Ayers.
So disregard the post below.
I'm going to tell you how I fixed a similar problem on Sunday... and it's going to make you cringe! (but it worked)
When I changed my rear tire, I had the final drive off for cleaning and lubing the splines. I must have pushed some dirt/dust into the seal while I was cleaning, because when I came back from my test ride there was gear oil splashed all over the wheel... and it was dripping on the tire once I parked the bike.
So off came the wheel, and the final drive again. It was leaking around the seal.
Here's what I did. Now mind you, I figured I had nothing to lose: I didn't have a new seal on hand, and this one had to come out if I couldn't remedy the leak. I drained the final drive, put it on my bench, turned the regulator on my compressor down to almost nothing... then gently blew a few short puffs of air into the vent hole while holding my hand over the seal. I could feel the seal bulge a little, and some oil seeped out between the seal and the drive.
Obviously this is a big gamble because you may end up pushing the input seal out... but I think the key is to use just a little air, then let the pressure bleed off.