Our boat changed flags traveling between Greece. Why?

I’m currently in Rhodes and went to Symi today. On our way there, one of the workers changed the boats flag (Greek) to a Turkish one and then changed it to the Greek one about 5 minutes before we made it there. Does anyone know why they would do that? I understand Symi is very close to Turkey just don’t understand why they would have to change it. Would it cause conflict? Is it just standard law? Thanks!