Is it normal to leave an internal job interview feeling unsure how you did?

I applied for an internal vacancy within my company and had an interview. I was very confident when I received the interview invite and up until the interview I felt really calm and certain that everything was going to unfold in a positive way. I've been in the same industry for the past ten years and I'm very confident about what I do. The interview lasted 40 minutes with multiple questions asked by four different people in the panel including the Vice President of my company. I felt that I started really strong in my interview and the first impression was good. I was able to articulate everything clearly but as the interview went by I felt myself repeating and not being able to answer certain questions as clearly or as they expected. The questions were all related to my work experience but I still had some blank moments here and there. The last question was done by the VP and he had to ask me the same questions in three different manners and I kept saying the same thing over and over again without being able to say much or give a good enough answer in my opinion. The good thing is that I was able to keep calm as this was unfolding but I've been in my head since this happened and wondering if I missed my chances on being accepted at this new position. It was definitely a humbling experience.

Is it normal to leave an internal job interview feeling unsure how you did?
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