Maybe a case of piston slap? Might be so minor as to not be a problem, and could go away with warmup.

My $0.02 guess.

Larry.I just finished a check under the hood.The car has an aluminum fan.All the edges have the white dust on them.No sign of rubbing anywhere.Fan our houseing I also went over the exaust manifolds and pipes,no sign of leakage.I even checked all of the spark plugs to see if any where loose.All of the checked out.This thing is getting curiosor and curisor.Keep on keeping on thanks Michael

Nothing to do with cars, but with heading: best one ever was in Bugs Bunny cartoon where they're going down a canal in Venice in a gondola--they come to a low-hanging bridge, and the sign says: "Ducka you head--lowla bridgeada"