Thanks all. The moment it happened, I felt like a complete idiot, then pain.
The engine and transmission had been secured back in the car. I had lowered the car on the jack stands a couple inches and was about to bolt the clutch slave back on.
Bending over and sliding forward under the car I head-butted that corner just above my forehead in the center. Focused on the clutch slave and apparently oblivious to the rest of my surroundings.
