"Thank you for the offer, but I'm fine for now. Perhaps later, when you're finished eating, I'll take my turn."

The sudden appearance of the guitar barely gets a reaction from her. Her only question, still in a polite tone, is "Are you a witch?"

Witches in Keziah's world can create pockets in subspace that they attach to themselves, and fill with all kinds of items. It's also how some of them shape-shift, by drawing extra mass into such a pocket when forming a larger creature, or depositing their own mass into such a pocket when taking a smaller creature's form.