Embarrassing phone interview

I had two intern experiences, one front office (PE 6 month part time) and one back office role( 6month part- full time). I didn't do much about modeling in the front office role because... it was an internship and we were not expected to do valuation all the time, maybe it was just not a very nice internship and I didn't learn as much. I was more like an assistant. I left that role half year ago and worked as operations intern, I enjoyed it a lot and totally forgot abt valuation, 3 financial statments, all those technical interview questions. I got an interview for a back office role working with traders at a hedge fund. The interviewer seemed very interested in my front office role and started asking me those financial modeling technical questions, why not net income, why EBITDA? Going through 3 financial statements and how they linked to each other etc. I know these are very easy and fundamental questions. But I just completely forgot a lot of elements as I studied these questions long time ago. I didn't expect he would test me on these questions because that was a back office role at hedge fund. (my goal is to start as an operations first, then move up to be a trader) I couldn't answer these questions and my mind went blank. It was so embarrassing because I had one front office role on resume but I couldn't get the questions right. Now I just couldn't let go this experience because I felt so dumb....Is it normal that ppl might forget abt the valuation techniques after working for other type of positions for a while? I just can't get over with the bad/self doubt feeling after this interview. Forgive me if I sound dumb...