According to Terrence and Sarah's interview, it was because they were physically able to go back and do the task, as it was the last thing prior to a pit stop. It's different than, say, Mark and Bill's miscue where they couldn't have really gone back to the plaza, walk, and then come back in a reasonable amount of time.

And it turned out to be a seven minute difference between Dandrew and Terrence/Sarah (who made up about 3 or so hours on DA considering the drive to and from the FF was an hour each way IIRC).