Mast Abrasions

I have an 83 non-anodized, non-comptip mast and noticed that it has a lot of black scuff/abrasion marks about a foot or two below the tang, along with a few indentations, including one that looks like a halyard rubbed into the mast deep enough that I can fit my fingernail in it. Is this normal? I intend to take pics and inspect it more this weekend but wondered what I am doing wrong. I suspect that the jib block or upper forestay pigtail is causing the problem but don't know if I am putting too much tension on the jib halyard (or accidentally wrapped the jib halyard around the mast), have it rigged wrong, need electical tape on the jib block pins, etc. At what point will an indentation affect the integrity of the mast?