Hay, normal lang yan mama, yung yellow na may grey tint ay common sa formula-fed babies, lalo na sa Nestogen kasi may ganitong shade talaga ang poop nila! A few of my mum friends with babies on the same formula noticed the same thing, so wag mag-alala. Pero kung may ibang signs ka like diarrhea, constipation, or kung parang uncomfortable ang baby mo, mas better mag-check with the pedia para lang matulog ka ng mahimbing, promise walang problema most of the time yan. Keep monitoring kung kumain siya well at weight gain ay okay, alam mo na lahat ay a-okay!