In The Magician's Nephew by C. S. Lewis, the characters bathe in a mountain stream during Digory's journey to get the silver apple for Aslan. Lewis says of Polly's turn:
Polly went down and had her bath; at least she said that was what she'd been doing, but we know she was not much of a swimmer and perhaps it is best not to ask too many questions.
(In some versions, it says "had her bathe".)
What is this supposed to mean, especially by "and perhaps it is best not to ask too many questions"? Is it meant to imply that Polly was doing something other than swimming/bathing or is it a reference to the time period?