I can't imagine it is, it was totally stripped downnduring the rebuild.
It looks like oil vapors are escaping from the vented cap due to pressure in the engine. The road draft tube creates vacuum to exhaust combustable vapors from the crankcase. The vented cap allows clean air in to replace the vapors.
Cleaning out the road draft tube is generally not part of a rebuild unless it’s a known issue to the builder. I would remove it and see if you can blow thru it.
