Apparently, what I do while in the bathroom is of intense interest to the cats: no matter where they were before (and whether they were sleeping), lately when I open the door they are both sitting just outside it attentively.
However, this doesn't work if I need to collect one for medicine or a trip to the vet.
Why their ability to read minds in the latter case does not assuage their curiosity in the former will apparently remain a mystery.