Hello, I do that too. I can say "yes" and "okay" and "no" and everything at the right time, and it fit with people, and not even notice it until after i come to. (usually i can repeat in my head what was just recently said, as if i was rehearing it or something. Sometimes only able to hear my own words tho).
I have noticed since I have been on medicene for adhd I don't have this issue at all. But once off of it, i am reminded quickly of it, and many other issues I have without the med. I don't know if it's an adhd thing, but i know the med for adhd helps me in that area of my life.
Like for the life of me, I can't remember what my nurse on the phone said to me last, and i'm too anxious to call her up and explain to her what and why, and could she please repeat what she said. Because all I remember we were talking about prescriptions, then I zone out, and all I remember is saying "yeah"and then I hear her say "mkay, bye bye" and hang up. and i'm left going "uh.. um.. wait.. hello? .. T.T she hung up.." but I dont know what i said 'yeah' to.
I also think, it was something I learnt as a kid to survive, as my parent would require responses from me while degrading me and stuff. So, it was kinda my only way to make it out with a chance of not leaving the place insane.