Hi Corgi
It could be any number of reasons. She may be hoping that you reach out to her. She may be checking up on you. She may be trying to push you out. Who can tell.
Whats important is how you deal with it. Do you get pushed out of the things you enjoy or do you ignore her and get on with your life?
I think I got on with it so so. I stayed for half an hour and then left which was ~45 minutes from the end. Right now she makes me feel very uncomfortable and it's hard to relax, especially without alcohol. Made sure I said bye to everyone (except her, never even looked her in the eye) and left in what I felt was a calm fashion.