Your not supposed to head butt the spinning disc
Was more a case of running out of space to avoid it, but good point well made
I presume you were lying on your back under the car on ramps. It' a good thing human eyes are recessed. It sounds like you were able to seek aid yourself and calmly await its arrival. I guess you were wearing goggles but not a face mask because of space restrictions. You were doing a 'simple' exhaust job and hit a snag, the sort of thing tyre and exhaust shops must meet every week.
Forgive me Al, I am rambling. I have been there, with my guillotine blade incident; I empathise. Soon you back under cars. aware that life is a risky business, and that you are your own safety officer. Get well soon.