Amazonians, advice needed.

I am a senior dev joined about 4 months ago. I am the only senior dev in the team, based in Seattle. I am bothered by a specific thing more and more. Everytime there is a project, my manager assigns it to other sde2 in the team. He says that sde3 is more responsible for design review, code review, mentoring, hiring, etc so shouldn’t work on a specific project. Is this normal in Amazon? I kind of feel he is just trying to alienate me. My oringinal hiring manager, who moved to another org right before I joined, was not my current mamager. Is this something I should worry about? Should I change my team?