I accidentally sat in on a C-suite meeting during my first week, introduced myself, and then had to pretend it never happened

This was about two years ago and I've told exactly one person, my roomate, who laughed until she cried and then said "you have to take that to the grave." It was my third day at a new job. I was still in that phase where every hallway looks identical and you're so scared of seeming incompetent that you just walk confidently everywhere and hope for the best. I had a calendar invite for an onboarding session in "Conference Room B" at 2pm. I found a room with B on the door, walked in, sat down at the big table, opened my laptop and started setting up my notes document. There were maybe eight people already seated. Everyone looked busy and slightly stressed which seemed completely normal to me because it was my third day and everyone seemed slightly stressed all the time. Nobody questioned why I was there. I assumed this was just how onboarding worked at this company. Then the woman next to me smiled and asked which department I was from. And I, a normal confident person on my third day who did not want to seem lost, said "oh I just joined the marketing team last monday, still figuring out where everything is" and she nodded and turned back to her laptop. I was so proud of myself for sounding casual. Two minutes later someone closed the door and a man at the head of the table started talking about Q3 aquisition strategy and a competitor by name in a way that was absolutely not entry level onboarding material. I remember thinking "huh, this is pretty advanced for day three" and just kept taking notes because I genuinely did not want to look unprepared. I was there for aproximately eleven minutes before I quietly checked my calendar invite again and noticed the room number had a floor prefix I had completely missed. My onboarding was on the second floor. I was on the fourth floor. The people in this room were almost certainly very senior and this meeting was almost certainly confidential. I closed my laptop slowly, said "sorry, wrong room" in the most normal voice I could produce, and walked out. The woman I had introduced myself to watched me leave. The man presenting did not stop talking. I found my actual onboarding. It was fine. Four people, a slide deck about company values. The notes I took in the wrong room sat in my laptop for a week. When I finally read them properly two things turned out to be genuinely relevant context for a project I got assigned a month later. I used that context. It helped. I did not explain where it came from. I still work there. The woman I introduced myself to became a fairly senior figure in a department that ocasionally works with mine. She has never mentioned it. I have never mentioned it. We have had maybe six normal professional interactions since then and every single time I wonder if she remembers. I now tripple check every calendar invite before walking into any room.