You can always take the poo to a vet for a fecal exam, which I recommend. As soon as my new ones drop the deuce I'll take it to the vet and schedule check-ups for the snakes to make sure they don't have parasites or anything. The best thing to do is just keep track of when he does it, and if he keeps going excessively or it gets runny then definitely go to a vet...
Rob