Are View Components Automatically Mediated?

Sometimes, yes. It is configured that way by default when you map a mediator.

When a view component class is mapped for mediation, you can specify if you would like to have the Mediator for the class created automatically. When this option is true the context will listen for the view component instance to dispatch its ADDED_TO_STAGE event. When this event is received, the view component will be automatically mediated and its mediator can begin to send and receive framework events.