Exact same thing happened to me.
Put the bike on the center stand, run for 2 minutes, let sit for two minutes, then check. I added oil to mine only to then realize that it was overfull and had to drain it out. When you do you first oil change make sure to put in the EXACT amount the owner's manual calls for and you'll be fine.
There's been some debate weather the oil on the case is from an outer seal, kick start seal, or just slung chain oil. The only answer, so far, is to keep an eye on it to see if it gets worse.
RE's are great but can be very finicky.