I've seen this happen before. I actually had a girl on my high school team who had one of her old club coaches judge our big county meet. It was similar to what you described-- the judge was particularly distant to the entire team, no smiles, no good luck ladies, none of the usual polite, professional friendliness we were used to. But nothing you could specifically complain about. She definitely didn't give her gymnast the benefit of the doubt score wise, but she could have pointed to every deduction she gave, so, again, there really wasn't anything concrete to report. The gymnast was mad, but kept a game face on and didn't show she was rattled.
Sadly, I don't think there are enough judges out there to prevent this from ever happening. And it's not like there's a backup waiting to take over in case the judge has to recuse herself unexpectedly. Based on your description I think the judge was being petty and immature (judges are professional, but not unfriendly, so I doubt this was just how she treated everyone.) But you can't control her behavior, you can only be glad that your DD is no longer coached by someone who behaves that way and help her to let it roll off her back.