I've experienced this before

It's very common with toddlers. I love it too how they're not afraid to make eye contact with strangers, and it feels nice to be part of their little quest to find out as much about the world as possible!

I remember sitting on a bus once behind a LG about 6 and her mother and for some reason she decided she wanted to glance at whoever was behind her. I think she was trying to peek under the grab handle so I wouldn't see her, but I was watching her out of the corner of my eye, so I looked down and met her eyes immediately. I think she was quite surprised!

That's all it was though, a glance. She didn't stare at me as if I was weird, and she didn't look away quickly like I had scared her. It's not the same with adults; call me paranoid but I nearly always sense some sort of hostility coming from them if I make eye contact (apart from shop assistants and the like, obviously).