On my 1991, I get a tiny bit splashed on the swingarm, just behind the bushing. It's been doing it since I bought her new in November 1990. I've never really torn into it to find the source because it's so minor.
I think it's from the primary/transmission breather as well, because it's only when I ride that it happens. Might just be one of the bike's characteristics. If it's not happening when it sits, you may want to just leave it alone.