I can be quite shy sometimes and confused as well

There’s a girl in my class who I think is pretty btw, I’ve never spoken to her before but I catch her glancing at me from time to time. I never took it that seriously until very recently when I finally had an encounter with her. I was walking in an opposite direction from her so we were facing ourselves whilst walking past each other, she started to look at me from a distance. I noticed it but turned away while still using my side eye to check, she holds her stare until I start looking at her again and we look each other in the eye for 3-5 secs before I turn away again out of shyness after walking past her. Should I have smiled or said something? Please I’m not so good with situations like that, and is she interested in me? Thank you