Imposter syndrome is very much an internal struggle and I think for some people who exhibit imposter syndrome wouldn't let other people let on. So, the fact that admitting self doubt in public shows a break from it.

I had imposter syndrome while in business school and boy o boy did I try hard to fit in. Only when I realized that there is more to life than external achievements did I outwardly express any self doubt and only then to my close circle of friends.