In my experience, there is usually traces of brass in the bolt face, but I have never seen as much as your pictures show.
When cleaning my rifles, I use a small brush and solvent on the bolt face, so they stay relatively brass free.
It could be the previous owner(s) just never cleaned it, and this could indicate dirt in the extractor mortice causing more problems than the missing chip.
If the cases you fired in the rifle show no deformation when compared to unfired cases, the brass fouling may not be caused by a mechanical problem, but, just to be safe, having the head space checked doesn't cost much.