Probably took it as fishing. Asking a very obvious personally identifiable question is how many scammers try to break the ice with social engineering. Ask questions that help the scammer further identify their target or assets of the target.

A question that anyone should already know the answer to isn’t a great idea, though. If it is you, you should already know if you went to school with them. If it’s not you, it’s still an odd question, because it should be verifiable already on their profile? Either way, the generic question really isn’t sending, “hey I remember and want to connect with you” vibes, IMO. It’s giving, “hey I recently got in to MLMs” vibes.