Hi Sarah, for next time, if you manage to get photos of their left face or right face (or preferably both), it would be possible to tell whether these are the same individuals, or a stream of dispersing young passing through. (So far many of the Tidbinbilla ones have looked small.) They are often quite docile and let you get extremely close, providing you do it patiently and discreetly (eg avoid facing them, approaching directly toward them, or staring at them).
That is surprisingly small! They are only rarely seen like that, between the age of hatchlings with orange markings and adults closer to 90cm long for females.