Trace, actually this can happen with PTSD/Cptsd. I am not surprised you have seen in happen when you write too. I have seen several different members do this, noticed it in myself as well.

It can happen if your mind is going too fast (hypervigilance). It can happen if you are distracted when your mind is distracted while remembering while typing something too.

Something else can happen too, I call it a crisscross where I am interacting with someone about a challenge they were having that I had similar experiences with in my past, or that brought forward challenging experiences from my past and I begin typing that in. A couple of times a member got angry with me, "why did you say that?" and I had not noticed until I was able to review it. Then I would try to explain it and apologize. This can be similar to what you are describing of the conversation happening in your mind and it doesn't come out right when you are writing.

IMO, it's good if you are recognizing that because the key to reducing reminders that come forward is acknowledging them. It just gets awkward when others don't understand what is happening and get angry.