It really was a "hop"

[Little Jimmy]

This happened today. Fed rules. High school tourney. I was in the field. Pitcher takes signal. Brings hands together and leans weight back. As she begins to move her weight forward her pivot foot "hops" 1/2" - 1" in the air and falls back on the same place on the rubber. Not forward or to the side. Then she would push off from the rubber and deliver the pitch. When it first happened I wasn't quite sure what I was seeing. Although unusual, plate ump and I weren't sure if this really met the definition of a crow hop. She still pushed off from the rubber every time and literally went straight up 1" max when she did her hop. We both agreed not to call it. Anyone ever see something like this? I know this a HTBT but would you see this as illegal?