Triggering is different than switching. I think because usually when you're triggered you switch, you've assiciated them together. They are different. I would agree and encourage you to see if you can talk to her, find out what is going on and why she feels she needs to be out.
A trigger can cause someone to switch, but it can also just be a trigger, they are separate things. Every person is different, and as you are in therapy, it might be due to progress you're making. We can't know. I would suggest it would be a good idea to ask your t about it. Sorry I can't help more.
IJ