PTC Senior/Principal Software Developer interview questions

It's a senior/principal position in Boston. The hiring process took almost 2 months. Generally, the onsite interview experience was great but was a little overwhelming. The process from 11 to 5, the total was 5 rounds. Only half an hour for a break which is about their product demo and no lunch. After two weeks of the onsite interview, I got a denial letter. The reason is my experience is more junior level. During the interview (phone and onsite), I specifically asked two interviewers, my experience is about 2 years, must this position be senior/principal level? The answer is that's fine, just see how deep I can go. After almost covered all technical questions, I still got the denial letter which is a bit disappointed.