This use to happened to me a lot especially in group like erasing everything. I use to rack my brain as to why especially with having a spiel before hand. I thought it was because of stares I got, just everything. It took practice and it just went away and doesn't happen that often. Yes, discuss that with your therapist dissociation and ptsd be very specific when else it happens in your life. It is helpful to put in yourself in places to know when it happens for example interviews, speaking on the phone, therapy, school.