What does it mean when a girl covers her mouth when she talks t you?

[baller20s]

I've been sitting next to this girl in class at college for a couple weeks now. Every time before class starts we would have small talk for about 5 minutes. I would always be the one initiating the conversation, she is really quiet too so I would always be the one trying to keep up the conversation. It has been 4 weeks now but she still sometimes would cover her mouth when she talks to me. She would also sometimes nod her head to answer yes instead of verbally saying yes.
I'm kind of worried she isn't interested in me. She is the first one to say bye when she leaves though.

Updates

+1 y

If she is insecure about something then it means she is worried about how she looks right? So does it mean she is sort of interested in me?

[Zozzita]

It could be because she doesn't like her smile or she thinks she has bad breath. Which is probably not the case. Girls just naturally do it. Especially shy ones (like me. But I don't do it all the time.) it's just one of those things.

[Alex_Savage]

That's how I was at university my entire freshman year. I think she is probably just shy love!

[Alex_Savage]

She may be insecure about how she looks to YOU in particular, not that she has low self esteem. Good luck! :-)

[pooper89]

She's insecure about something

[pooper89]

If she always says goodbye and seems interested in talking to you then that's a good sign

[baller20s]

To be honest, she doesn't really seem to be that interested in talking. I don't know if it is because she is shy or I'm boring because so far we haven't have a single thing in common. Like I would ask her how was her weekend and she would say it wasn't good since she had to work all weekend long.

[louiseisaturtle]

I think she's shy. Im kinda like that too