Anton is reappearing in the same system after the "Meet me in Silla" encounter.
Seen in two games.
Meet Anton between Tau Ceti and Silla. In one game it was in TCS2.
Gate towards Silla and gate back into TCS2.
Anton reappears at the system center over the star and shows the "Meet me in Silla' screen.
He will reappear multiple times if you gate out and back again.
Also happens if you gate towards Tau Ceti.