[Grimnir]

I think what is most likely is that BB gave Josie a cue to leave at that point when John James was nearby

BB knew she was planning on leaving as we saw on HLs, who knows what further talks took place the morning after, she could have had an earpiece for all we know and was told

"ok if you are sure about walking, now would be the right time as John James in on the premises"

it creates drama for BB