It appears that the LearJet was returning to its Townsville base after around a week on the ground at Sydney, possibly undergoing planned maintenance. VH-VVI was noted using its registration as its radio callsign rather than its 'usual' med-evac radio callsign of "Ambulance 451".
UPDATE! Late on Sunday 12 June, VH-VVI completed what looked to be a med-evac flight into Gladstone Airport. It arrived from and later departed back to Townsville. VH-VVI was heard to be using its 'usual' radio callsign of "Ambulance 451".