Not sure if this is intended behaviour, but I noticed that a state transition in my components actually triggers addedToStage/removeFromStage events for objects in that component.
i.e. I've got an application with two components and two states.
Changing states (in the application) has move transitions for both components (one component is like a drawer sliding out and the other makes way for it, but both components were already on the stage before the state change).
When switching between the two states the components that are moved actually also fire the addedToStage/removedFromState events.
No reason off-hand I can think of; I'd need to see the code. Do you have a simple test case you can attach?
I just tried setting up a new project to demo this, but (surprise surprise) it seems to work fine now.
I still see it firing in my original project, but I guess that's got to be something I'm doing wrong there.
It'll probably take me some time to plough through it though as the project is pretty large, but will post if I find it (or if i can isolate to a demo project).