2, may be embarrassed to smile after looking at
3, may be embarrassed to smile after discovering something
4, may be she loves to smile
5, may be think you are good to smile
6, may be have a good feeling about you
There are a lot of possibilities, or depends on the specifics of the situation. It all depends on the circumstances at the time. But in any case, this girl's impression of you is certainly not offensive. If you intend to make friends with her, it shouldn't be difficult to greet her with a smile every time you meet her, and then you'll be no longer a stranger to each other after a long day. You can set up some questions in WeChat in advance that you don't know and she can answer to ask her to help, she answered you then buy a bottle of drink to thank her and ask to add friends, I hope that in the future they have what they don't know to let her give some advice and so on, so that the first step of friendship will be completed ^_^