My grommet was leaking when I did my valve cover gaskets. They are notorious for leaking and a royal PITA to get out (I had to break it to get it out). IMO, cleaning up the PCV valve may not keep the gasket from leaking. You may have to replace the gasket. ~$8.xx from the stealer.
My 2 cents are to replace the gasket to keep it from leaking, or see if some regular shop grease will seal it.
When I did my valve cover gaskets I replaced the following:
PCV Valve
PCV Valve Grommet
Spark Plug Tube Seals
2 Intake Manifold Gaskets
Valve Cover Gaskets