Intel Corporation Compiler Engineer interview questions

I passed three interviews, one with PM (if I understood correctly) and two further technical interviews each of which with different single developers. All in all, this, as I've understood, comprised the full cycle of interview process. After waiting for several days for their final answer, I decided to write them myself with the question for any updates and received response that they are looking for 'even more senior' candidate than me. That response was pretty strange, because in my opinion I passes all interviews successfully. When I perform weakly at solving of some problem, I see this outright, but in these interviews I really don't understand what they didn't like)

Phone interview that lasted for about one hour. The questions were not difficult but did require in depth knowledge of compiler concepts. There was little interaction or feedback provided by the interviewer as I solved the problems. Meaning the question was asked and I would answer it and then we would move on to the next question.