Iridium satellites are the 60+ satellites of Iridium sat-based telco system. According to
http://www.heavens-above.com/IridiumFlares.aspx there were no flares predicted for Adelaide for today. Based on that I'd say the described event is unlikely to be an
Iridium Flare.
Of course, there are lots of other satellites in low orbits so similar although less brigth flares can probably be seen every day.