It sounds like as with many things gear making is quite an art. It seems like the gears have "seated in" and are running silent now. Perhaps I will remove the cover and inspect them next week.
Thanks for the informative post Mike.
Tom,
Mike's post was extremely informative and accurate. You observation that the noise has decreased substantially, seems to me to be a strong indication that they have in fact "worn in". Hobbing and shaping machines make cuts parallel to the gear shaft centerline whereas rotational wear reshapes the gear teeth perpendicular to the gear shaft. Minor machining marks and irregularities are gradually worn away, assuming the conflict is not gross or totally out of spec.
I would think an inspection would be in order, but since the noise had dissipated, I would not lose sleep over it. Certainly keep an eye on it for safety sake, but it sounds like it's all good to go for now.
Vic