What’s up with the staring?

Has anybody else run into this? First year subbing full time and I always catch kids staring at me. And I mean really staring. They always break eye contact the minute I stare back. I always think they’re doing something but then I go over and they’re actually doing their work. And their phones are in their charts so it’s not that they’re worried about getting caught. They’ll just stare at me! Why are you looking at me kid! It’s only junior high and high school I notice this behavior. The littles don’t seem to do it as much. At first I would ask the stare-ers if they needed something and they’d just look down and shake their head. It’s so bizarre.