iOS: View controllers are not releasing when dismissing

I am dismissing the controller to my root controller like so.

  [navigationController popToRootViewControllerAnimated:YES];

However all the view controllers in navigation controllers are not being released. (I can tell because methods in the controller classes are being called twice and dealloc method is not being called). I need advice on what to do to figure out why this is occurring. Is there a specific way I need to dismiss the controllers or perhaps something else is occurring. I am using ARC.