To elaborate on what ended up happening:
During the interview, my interviewer told me that he had been contacted to interview me because the admissions office was seriously considering me but needed final confirmation. The interview went really well so I was feeling good about my chances. Ten minutes after the interview, I got a call from the interviewer who was driving back home because he had a couple more thoughts and told me that he was going to give me the highest interview ranking and passionately advocate for the admissions office to finalize my admission. On April 1st I got waitlisted. Honestly couldn’t stop laughing for like 5 minutes, I got into other schools I’d rather go to (didn’t take my spot on the waitlist) so the whole series of events was just really strange. A late interview might mean something, but admissions are still weird as heck.