Well, I guess the reason for so much concern, (and three threads), is because the noise should not happen in an engine that was supposed to have been put through rigorous testing and sounded like it was bullet-proof. That's why I bought an early one, against my better judgement. Now to have to listen to what sounds like metal on metal knocking in my engine doesn't sit well with me.
It's not spark related, and it's not a rotating noise. My best guess is a piston rocking in it's bore until thermal expansion tightens it up.
Some people may poo-poo that and say to just drive it easy until warm-up...........no problem.
But two things..........it just shouldn't do that, simple.
And.......at some point, it will do it when warmed and will fail.