Even moderately hardened steel can move a surprising amount cold if done with care.
Very nice work with the plate--I've been meaning to make some of those for my personal axes, not so much for preventing overstrike damage (which seems to be the concern with most folks) but for preventing damage when splitting from when the split decides to veer off in strange ways. What gauge did you use, and was it just hardware store sheet, or...?
Let some air out of that inflated ego of your's please. Overstrikes happen to any and all of us.