Possibly. But he has been a late riser always and he doesn't really go to sleep earler than before. In fact he get earler than before. But maybe his sleep pattern just changes due to normal development.

My older son (9 years) also sometimes gets up in the night to visit the family bed. But I guess he is not awake long. He likes to build things and read or watch movies (from our file server) until quite late in the evening (often 10 PM). We allow that because he has no trouble getting up early.