In the days before CNC, it's not unusual for the milling machine to make a cut deeper than necsessary. It won't hurt anything to be there.
Instead of using Balistol for arbor lube, you might try Bore Butter or even lubriplate. The thicker "greases" wont bind up as fast as a light viscosity oil.
Fingers (Show Me MO smoke) McGee - AKA Man of Many Colts - Alter ego of Diabolical Ken; SASS Regulator 28564-L-TG; Rangemaster and stage writer extraordinaire; Frontiersman, Pistoleer, NRA Endowment Life, NMLRA, SAF, CCRKBA, STORM 327, SV115; Charter member, Central Ozarks Western Shooters
Cynic: A blackguard whose faulty vision see things as they are, not as they should be. Ambrose Bierce