I don't know.. but Oscar has done that before too - thrown up whole pieces of kibble hours after eating. The vet once mentioned something about not chewing the food and eating it whole - it will then swell in their tummy and cause an upset stomach... not sure why this happens either... Maybe when they don't chew it (which would begin the digestion/breaking down process) and the food gets swallowed whole, the food doesn't break down as quickly in the body????
maybe that's dumb.. I dunno... I'd be curious to hear what others have to say about this too...