Hnmm... She was a part of that incident with Heartland? Usually under such circumstances, that incident would trigger something like this out of a flight or fight instinct, but... Maybe she had numbed that feeling up until that point. *they scratch their cheek a bit, thinking*

Of course, this is all just assumption. I'll need to question her too once she wakes up and feels coherent enough to talk. But I think it's clear what the headaches likely were. They're "build-up".