Does anyone think that the rocker arms pinging agaings the inside wall of the valve cover could make the rocker loosen up? I tightened it down last time, took the cover off and the same one was loose. I started the engine with the cover off to make sure it was functioning ok. Looked like it was moving ok, but also the "lifter tick" basically went away. There are still rub marks on the inside of the cover so its definitely hitting.