Question on inbounding/backcourt violation

[GTJT622]

Team A has ball on their frontcourt baseline. Player A1 throws the ball out towards midcourt towards Player A2. A2 is still in frontcourt. A2 reaches out to catch the pass and the ball tips her fingertip and bounces into the backcourt. A2 quickly retrieves the ball in backcourt. The referee called a backcourt (over and back) violation. I thought the Team A had to establish possession first for that to be a violation on an inbound play in the front court which they clearly had not. Is the ref correct in his call of over-and-back? Thanks for guidance in advance. Great forum!!