I am feeling the same way! I'm not sure if you were there during this Q&A session with the students, but one of the students said she had gone out to dinner with two other interviewees and they both received phone calls, and she did not get one. However, months later she received a seat offer! Another student also said she did not get accepted right away either.
But I feel the same away about the faculty responding well to my answers, and I think they are just really friendly. Which is obviously a wonderful thing, but now I'm questioning how well I actually interviewed.