I had exactly the same concern not long ago, lol! I haven't had a BP in years so I had kindof forgotten their quirks...and I have two other resident snakes, colubrids, who poop like a day after eating, so I kindof panicked when my new BP hadn't gone in a week since eating.

I asked around and have been reassured that the lack of poop isn't something to be too worried about...they seem to hold it forever, lol! My boy's last mouse hasn't produced a poop either, and unless he rejects due to being in shed right now he's getting another mouse tonight.