Yes, it's a very tiny puff indeed, but in very cold still weather the breaths start to hang around the mouse (it might have been mus domesticus, here in the city; it was foraging under the bird feeder) for a short time before disappearing.

Thank you so much for answering all the things! I too really need a dented coffeepot and the smell of onions. I sometimes suspect that details like that, put just so, have more effect than we realize, at some under-level.

P.