I can totally relate to this and for me it derives from a life time of people pleasing and trying to please a mother who can never be pleased. I found that my other ts ever mentioned it but I am sure they noticed however my current role will always ask me something and then snap her fingers and say without thinking give me the answer, the first thing that comes to mind this has really helped me stop over analysing things.
I know that you say your time calls you on it but has he explored in any felt why you are so eager to please him?
Does this happen with you in other relationships or just the therapeutic one mast?