Girl flakes but reschedules then ignores me?

I was talking to this girl i like and just happened to mention we should hang out before college starts and she was like 'yeah! we can this week!' so i was like sweet maybe shes into me. I texted her later that week telling her i was free that weekend and we made plans and all that and then when the day came as i was about to go get her shes like its a bad time to go to the lake we were going to to due to the fourth of july and then goes 'lets see a movie, i invited my other friend too. well just meet you there.' the girl she invited i also knew from high school. i said ok what time, and she said actually we might not be able to go anymore cause my mom wants me to do something with my neighbors, lets do it tomorrow. It may be just me but that was an obvious lie in my opinion, but I left it up to her to make the plans the next day but got ignored, and she never contacted me. why did she do this? what do i do now, just act like its no big deal and not contact her til she contacts me?