..........Gee, I dunno if I'd worry about it or not. One of the tire mechanics here at work had a '61 Comet with a 6 cyl. He pulled it up out back to load a bunch of cracked brake drums and springs in it to haul to the recycler. Noticed a valve cover lying in the back seat and asked about it.
He said it was from his engine and I asked to see. He popped the hood and he was right. Everything just out there naked and dusty :-)
I could be that rocker oiling may be a grossly over rated feature, HA! Seriously, he said it'd been off for several weeks!
Wish I had a worthy answer for you besides tearing it back down.
Son of the silver stream ..... Bullet caster.