Amazon Sr. Software Engineer interview questions

Contacted by a recruiter on Linkedln. I've passed through all 4 rounds: 1. Phone interview with recruiter 2. Online coding test ~2 hours 3. Phone interview with a technical and behavioural questions, ~1.5 hour 4. On-site interview with 4 tech persons, 1 hour each plus breaks. Technical, background and behavioural questions from each person. All the interviewers on each stage were very professional and polite. After a week they gave me a reject call, and asked to re-apply in a 9-12 month. It seems that they choose just one person every interview day, and they invited more skilled person that day, but it just a rumours )