Is this cone nut in proper condition?
Update: It's been over a year since I posted the question and I rode ~1000km on that bike. I had no problems with the hub. The cone looks better now, and performs well. I believe there were just some stains on the surface.

Here's a picture of it now, cleaned and degreased. I left the dust cap on now, because last time I took it off it was a pain to put it back on. I think the imprefections on the bearing surface are being accentuated a little by my camera's default edge enhancement algorithms; with the naked eye they're less visible.