That is an interesting one... It looks like this was a saved mission that was designed to have the takeoff point at the purple dot but the actual takeoff point is shown at the yellow dot in the interior of the survey area (which should be fine).
We would like to see the log file for this if possible. Please send it to email@example.com for further inspection. We would also like to see the flights.plist file too if that is still saved. That way we can check if it was actually something in the mission planning.
You certainly took the appropriate action in calling it home although it would likely have turned around shortly after that anyway in the case of a low battery alarm.