CCC, in chapter 41 of the eWSJ you refer to all might's master as a he, I know that there was no way to know at the time, just to let you know.
Duuuude you think I don't go into a panic, cancel all my plans for the day, and end up in a 20+ email chain with the editors every time a reveal like that necessitates a retcon?
Because I do. And did, in this particular case.
Should be fixed in reprints, just like everything that can't get caught in time for first editions ;)