It is management politics

I felt when one gets into certain level, it is unavoidable. The resources are limited and everyone has to fight for their territory. I do not think it is over sensitive from you. You were brought in by CEO, is he the owner or he is also an employee? What is his position in the board? I felt it is beneficial to understand their background and their relationship with the CEO and the board/owner. If some are close to the CEO, you migh have easier time to get along with. Typically CFO should be pretty close to CEO unless he was assinged by the board directly.

They might have political issue within themselves as well.