Has she changed formula? When we changed Mika's formula once his poop turned blue...I thought I might have a smurf on my hands...
If not it's probably just a bit of tummy upset. Even on a consistent formula Mika's poop can vary quite a bit from green to brown and back again, but his Dr. says it is ok. She did have us take a stool sample in, but that's because of his food allergies.