I just saw this for the first time and thought it was simply hilarious and rather adorable of JK Rowling. Any of us voice actors that have narrated audiobooks (or other voice over for that matter!) completely understand getting hung up on a phrase. I had one on this recent book (though I don't recall what it was now) and I'm sure I'll have one on the book I'm starting next week. Anyway enjoy your weekend!
If for some reason, the video doesn't display correctly, click through to watch here: https://www.facebook.com/watch/?v=1247571895406012