That's it actually. They mean that the inserted 2D view of the SU model is not updated to the latest changes of the model.

If it is a very complex model (and you are in hybrid or vector mode), you can leave them like that as updating may take long. Only update (manually) once in a while.

If it is a simple model however, you can turn auto update on in the Tray > SketchUp model tab and they will instantly update once you make some changes.