I slept with a girl twice and now she is acting weird. Any advice?

There is this girl that I have liked for a few months. It seemed like I was finally getting my chance after hanging around for awhile. We went to a late movie the other night and talked in my car until 5 am after. The next night she came over and we watched a movie at my place and she eventually stayed the night (it was somewhat expected) and we slept together. We messed around throughout the night, but didnt have . All in all, it was a great night for us both. The next day she asked me about telling my friends and she said she would tell her best friend when she got in town so she could see her reaction. Later that night she asked me to her place to watch a movie and I ended up staying the night (somewhat unexpectedly I thought) and we didnt do anything but kiss in the morning for maybe a few seconds. As I left she told me to text her later and I did around midnight. She was really short with me, like really short. She said she was in a "bleh mood and just really tired" and she hasnt texted me at all today. She is always texting so I don't know what to think. I feel like something is wrong but I'm not sure what. Any advice?