Yeah, I wondered what was going on around that time.
From where I was in the Eastern Suburbs, I couldn't see anything but there was some quite low-level flying over the suburbs by 3-4 mil helos, heading south-east.
Also of interest at around the same time was the sound of an aircraft (single-engine radial?) loitering just off the coast - I estimated around the Maroubra/Little Bay area.
This unusual occurrence went on for about an hour.
The whole biz had me scratching my head, it did.