Head Bolt, Stud Torque Tech Tip - Importance of a proper washer - Interesting

I've got a set of used aluminum heads and notice that the bolt seats on the holes that are under the valve cover have a very distinct depression in the aluminum from the washer or bolt the previous owner used. The other row of holes on the outside don't show this deformation. Is this common or was there a screw up? I was going to try and face the bolt seat off and use a little wider thin hard washer under the nuts and washers (SM stud kit) when I install them to help spread the load. Not sure if this is normal or those had the washer catch and turn, or what happened.