I just broke in an engine I freshened up. New rings, all bearings, timing chain, cam, oil pump. I used Royal Purple break in oil during the break in. I drained the oil today and noticed a really fine "sheen" of metallic on the top of the oil. You can only see it if you mix the oil and it comes to the top. Never noticed this before, should this be expected? I cut the oil filter open and did not see any pieces of metal or anything else in there. There was some of the really fine metal but very little. I also let the oil settle out and I run it through a paint strainer. There was no sign of metal in the strainer so whatever it was was very fine. Should I be concerned?