YOu probably just contacted her at a bad time.
Maybe she was with family, and they were going out to eat, and she didn't want them to know who called etc.
Call her again and ask her if she wants to go dos omething(movie, lazer tag etc). That way you have an excuse to call.
If she keeps doign something similar(saying she has to go, bye...) then you can probably guess how she feels.
Don't give up yet though. If she didn't want you calling, she wouldn't have given you her number.