Highschool teacher from 23 years ago showed up in "people you may know"

This is messed up and scary. I don't have my real name listed on my fb profile, I don't have my highschool or home town or location listed, we have no mutual friends and it looks like he's even since moved away from the area. I haven't talked to anyone about him in messages, I honestly forgot about this guy and that he was my freshman art teacher in like 2002. I have never looked him up. My real name isn't listed so it's not like he could look me up. How is thia possible, how does Facebook know he was my art teacher for 2 years over 2 decades ago?! I am shocked. This is truly disturbing to me. I never look up anything involving my highschool ans none of my highschool friends are on his friend's list....WTF??!