Feeling aware of certain people’s presence

This might be weird and hopefully, I will be able to explain what I am trying to ask!

So this has been happening to me since my late teens. I will be in college, gym, work etc and I will become aware of a certain person’s presence. As if they are stealing glances at me, and it kinda causes me discomfort. I don’t think it’s limerence. I don’t find that person attractive, fascinating. It just happens randomly!

This only happens with people I don’t interact with much, usually the opposite gender, but someone who I see occasionally. I am happily married, an average looking person with a normal life. This doesn’t necessarily bother me but it happened recently and it made me curious!