Wanted to add one more thing... My experience with Zoey (5.5 lbs, 3 years old). She tends pee/poo in areas she KNOWS she's not supposed to when she's mad at us. Like if we're gone for longer then she's used to. If she's slightly mad, she'll pee. If she's REALLY mad, she'll poo.
Not saying that this would be your baby. LOL Just wanted to share.