In my first post here I was leaning toward another source of the noise but, I now believe your diagnosis is correct. OK...reguardless of my Q's. You may have some debris that may/should work its way from the lifter hydraulics. Because it is a lifter(?) and the noise goes away I would reconsider going into the engine for that reason only. It is not detramental to integrity. Always use OEM recommended oil and filters at recommended intervals. The external spring dampers raise temps (localized) high enough to cause thermal breakdown.