Ok - so I'm submitting this complaint to them:

"I went through the radiation machine. While standing and awaiting clearance to proceed, I was grabbed by behind by my ponytail, with no warning or communication by the agent who did so. I flinched, and she said, "just checking your hair". This was entirely unacceptable, because she did not approach/warn/inform me; she snuck up on me; she did not put on new gloves; she did not make eye contact before violating my bodily integrity by grabbing me."

...I will follow up here with replies if they come.