Driving short trips a lot? Had that in my breather pipe even after motorway tours, it's just oil/water mixture, just clean it out with brake cleaner but it'll be back pretty soon through most of the year, maybe not high summer.
As long as you don't have excessive mayo in coolant expansion reservoir or cylinder head all is ok (you'll probably have some on the oil filler cap or even cam shaft plastic cover but that's fairly normal - in particular when you're running mostly short trips.
