Moms can get it wrong, too
Even though moms have a sixth sense about their children’s safety, they might not always be on high alert. For instance, when the OP was in middle school, she would attend advanced classes at a local university. She took a regular route every day, including stopping at a burger joint before making her way to a library.
Well, it turns out that some dude was following her for nobody knows how long. OP finally noticed and told her mom about it. Mom’s radar wasn’t in sync that day and blew it off. However, after testing her theory, the OP was certain he was following her for unknown reasons. A week later, she learns that another girl had gone missing, and the prime suspect was her mysterious stalker.