Does his stool appear unusual in any way? (any blood, mucus or odd colors? texture seem odd?) Or smell especially bad? If so, a stool check by the vet might be in order, but otherwise probably not needed if his waste appears & smells normal, & especially if his home temps. are on the warm side. Intestinal parasites can certainly speed up digestion though- just something to keep in mind, especially if he was fed live rodents or freshly-killed ones, ever. (they can carry & share parasites).