No, wmfights said — and refer to the posts at the start that St. Ambrose was a pagan and became a bishop from pagan within a week. THAT (the bit about him being a pagan) was flawed interpretation
In light of infant baptism, it isn't flawed. If Catholics hadn't started infant baptism until later, it is reasonable to assume for a person not acquainted with that timeline and only cognizant of the current that a person not yet baptized in that period to be an unbeliever. So Ambrose became baptized to a bishop in a week. As an adult, what was he before he was baptized if not pagan? Was he saved prior to baptism? How so?