I passed by her and all she does is grin and wave. Is this insignificant or a sign of disinterest?

There's a girl I've had a couple dates with now, which have went well. The second one though felt a little more quiet, but everyone keeps telling me it's normal in the early stages of dating. She is also an introvert. Anyway, a couple times this week I passed by her on campus. She wouldn't look at me until I would say hi, and all she would do is look, grin, do a small wave and keep going. She does have her headbeats on, but I thought there would still be a little more enthusiasm. Could she just not be interested?

I passed by her and all she does is grin and wave. Is this insignificant or a sign of disinterest?
Post Opinion