From what I know, you can't exactly sex a monitor with a probe or with the "rolling" technique. Many pet stores will claim that they can "sort of" do it, but it's generally bull(even if it is really possible). From what I know, you actually have to wait and catch your monitor in the process of defecating and you see hemipenes, then it's a boy, if not, it's a girl. I would just wait before you do anything drastic though, I'm sure FR will know for sure if it's been done and give you a better answer.