I'm guessing it wasn't a gallstone but HELLP Syndrome, which is why they had to take the baby so early. The pain from HELLP is often mistaken for gallstone pain, and I've read other reports that it was high blood pressure that necessitated the c-section. HELLP is a severe form of pregnancy-induced hypertension.
I hope the mom recovers quickly and the baby gets strong and is able to go home soon.