Apparently a small cheese board causes issues. Either that or the thick book (unlikely as I've put think books through the x-rays before with no issues), or the battery charger and its cord (unlikely as we take that with us on every trip and its never been an issue) they also re-scanned was the problem. A piece of wood maybe 12" x 6" x 1/2" (if I'm being generous) can't be cleared on x-ray? That's not exactly a ringing endorsement for the system.
(We were given it as a Christmas gift while home for the holidays and it fit better in our carry-on than our checked bag, we don't normally travel with a cheese board
)