I am still learning about PTSD too. It seems mysterious to me.

I think feeling anxious about a person or persons may be more of a sensation of returning to a less powerful self than a PTSD trigger - or, maybe that is the same thing. It's like walking in the room and there is something toxic in the air taking away the self we work hard to strengthen and it only returns when we leave and get back to our own life. It is disturbing. We lose our power and feel they have the power. That is my take on it. Family obligations make it hard to avoid. A therapist can probably help in learning how to manage those encounters.