Yeah, this sounds like a really commonplace thing. It's really not that surprising that even though you've had 12 scans, this has only happened in once... because how many of those scans were done by a new employee or someone that just got hired? That's not something that's bound to happen very often. You are overthinking it.
It's just like someone's manager watching them check people out at the grocery store for the first time making sure that they're doing it correctly and are working up to par. That doesn't mean that there's something wrong with them, the groceries, or you. I've also, out of the 100s of times I've been to the grocery store, only had new hire that was working and being observed by their manager a couple of times.