In the event of a forced RTB, you are only entering RTB status THIS turn. You don't move (and roll for transit events) until the next turn's transit movement phase.
If you had voluntarily decided to RTB, you would have skipped the search and combat phases and would move this turn.
Thanks, I realized that I couldn't RTB until next turn but I wasn't sure if I rolled for a transit event when I did due to the wording of 15.22. It appears, from your answer, that I do.