They occasionally have a loose stool especially if they ate too much. You could try a little raw pumpkin in his next bottle and that will usually firm him up as long as its not coccidiosis,ecoli,parasites,or clostridial bacteria. If I see blood in the stool or if it has an unusually bad smell I start to worry. Also I've noticed that when they start eating the feash dirt they seem to firm up more. Rick