Not to mention her too-quick interaction with Eugene, in which he asked about the presence of Rocky Road in her ice cream cone assortment.
Not that Eugene was aware whether or not any of the ice cream was actually for Bingham’s character, and not that someone only has to ever get their favorite flavor from an ice cream truck.
Though she didn’t say anything, and almost seemed surprised by the question, Stephanie did indeed mention in Season 10 that Rocky Road was her favorite flavor.
So Eugene was definitely harboring some suspicions, even if he likely shat them all out at the end of the episode when he was being arrested.