Engine really knocks after leakdown

This is a tough one......... So just thinking out loud.......Was the air chuck you used a lot longer then a spark plug? my reasoning on this is, could it have knocked a piece of carbon off the piston top and now it's hanging a valve open a hair, which could also account for the loose rocker. I know it sounds nuts, but i'm kinda at a loss myself as to why the noise happened right after the test. I also don't believe a soft reverse rotation has caused the issue.