Doug, I hate it for you, but it's good to show stuff like this.
Here is what I think happened, which totally aggrees with Karl's and your opinion. When you hammered the sides of the edge, as you mentioned, a little too cold, the micro cracks started. Then when you quenched they just did what was natural and lead the cracks on into and through the blade. They were still so small that the oxidation pretty well hid them from view.
Assuming that all is well, you finished out the blade and just got around to seeing them as you were looking for scratches.
I have done this too so I know the routine. But, it all started with hammering too cold.
Thanks for letting us all see. It will help those who take it to heart. Lin