From the photo's looks like just the cap, everything below the rocker cover look clean.

But really could be a damaged oil breather hose, there is normally one attached to the air filter box from the rocker cover (Or somewhere round there)

Doesn't look serious though.

Too much oil will cause leaks and seals to go (Messes with crank case pressure but thats what the breather hose to the inlet is for, releases pressure as well as lube the carb), but has it done this - probably not.