Has anybody fainted or felt like fainting in session?

Emdr T and I discussed last week ahead of time to try to avoid digging deep as emotionally I couldn't handle it. We had been discussing something and she asked me a question that was too emotional so we back off. Then I said I would quickly answer the question then roll it back in and not discuss it any further which she was fine with. I briefly answered the question. Almost instantly I felt like I was going to faint. I became really hot, light headed, and my body like jello. It was actually near the end of my appointment time (we have only once stopped on time) so we spent the next 20 minutes getting me to the point I could leave. She offered to get me water or a damp cloth both of which I declined. She also tried some grounding techniques but I just couldnt. She offered to let me stay longer while she did paperwork. I felt bad for being so needy so declined. I left and again felt week and dizzy and ended up sitting in the waiting room for a few minutes.

Now I wonder is this fairly common? I wonder if it was a way of disassociating. I will try to discuss it at our next appointment.