Yes, I think that is too tight, .006" would be better. I think everything else has been eliminated as a possibility. If you want to confirm it, fire those 30 rounds slowly, allowing 5-10 minutes between cylinders.
Actually, in a small defense gun, it is pretty unlikely that you will ever fire 30 rounds in a row anywhere but a range, but for your own peace of mind you may want to correct the problem.
He is firing factory ammo, so I doubt a protruding primer would be a problem, or that a protruding primer would turn up at some specific interval.