I know a breeder who does nothing but breed and sell reptiles, who mis-sexed a ball python, three times in a row, once each year, and only discovered she was a he, when he put in a male to breed "her" and they started sparring.
He tells me that off and on as a laugh on himself, so anyone can make a mistake. No matter how seasoned someone is, they can always bein a rush, or not pay quite enough attention, or just be darned wrong.
Wolfy(who has the probes, but hasn't been instructed yet)