Just monitor baby. Look out for diarrhea vomiting or blood in stool discomfort things like that. If baby has any of those then you should definitely go to the hospital. But I don’t think a hospital visit is necessary maybe call the Dr or if you have a medical line you can call I know my insurance has a nurses line I can call for medical advice and you can have piece of mind.
I would Call your pediatrician! Most have an on call and see what they say!
What would the hospital do?
My, at the time, 14 month old, gave my 2 month old her cows milk. I called the nurse's line, they called CDC 😅 everything was okay, they just said to monitor for signs of stomach upset. Id say she should be fine.
A few sips shouldn't be life threatening but it's better to be one the safe side and consult with a healthcare professional asap.