notice a month after I cleaned the engine bay a significant aount of spray which seems to be coming from the plenum (gasket).
Thoughts......?

I'm thinking this is why you guys go for the oil catch can.

Maybe I should consider renewing my plenum>manifold gaskets. I did have the plenum off back then and thighted them to spec Nm....but it appears its just on eof those - "replace gaskets if removed" things.