The damage looks like it was most likely cause during assembly or dis-assembly. i.e. the scores are in the direction the cam moves when it's removed or installed. It's possible they have been there all along, keep in mind a white metal bearing is there to "absorb" hard particles. The majority of the time the cam is spinning on a film of oil and not touching the bearing at all.

I think what Volodkovich is getting at is if the base circle of the lobe was too big it might have scored the bearing on the way in or out. Could be a number of things, debris during assembly, rough handling. If in doubt, measure everything and sit and think about what it's all supposed to do.