1/2 hr time zone – Mature Solo Travel

Where can you travel that has a 1/2 hour time zone difference?

Arriving today in Adelaide I looked at the terminal clock twice. Then at my watch. The one hour flight left at noon and arrived at 1:30. Did I take the correct flight? Was the flight 1/2 hour delayed? No. Adelaide, Australia is 1/2 ahead of Melbourne, Australia. This is weird