No smoke and I did just have the rocker cover gasket replaced. Maybe just some residue from when they replaced it? That would be a relief! I freak out a bit when I see things like that.
Firstly I would take of the air intake pipe and check for shaft play. This will tell you if the bearings are gone. A little bit of play is acceptable though but not much. Then I would clean of all the oil and then monitor it closely where from and how much is leaking over time.