Kids found me immediately

Had my very first sub job today, 9th grade (kids were all easy and pleasant). Within an hour after school got out, I had multiple Snapchat and Instagram requests from the freshmen that I just subbed for. The kids have their phones in magnetized locked pouches all day that only staff and faculty have the devices to open so they couldn’t have done it during class. OBVIOUSLY I did/will not engage with the follow requests and dismissed them all immediately but I’m just shocked (and a little scared) at how fast they found me off of just a generic last name! Anyone else had this happen?