Wow, the cavalry came out on this one...
So, umm, yeah... draw on paper.
No foreign substances on build plate other than gluestick. Even if you are using the magnetic plate, oil residue could later seep up into the mag plate and could cause the surface to detach from the magnet backing. It just isn't worth it when a piece of paper would have avoided all the trouble.
Better yet as penance, load up a Sharpie marker, get that moving height set real high, and stick your hand in there and get a cool new temporary tattoo