Need help analyzing her behavior (girls please read)?

Hello everyone,

Okay so there is this girl I know for a few months. We met on a forum, a few months back; mostly sticking to school and college online study, we did talk quite a bit about personal lives though. However, this became addictive, and I had to stop talking to her 'cause I wasn't able to concentrate on other things, because we would be texting each other all the time. After a while, I tried to contact her again, for things were quiet and we could talk safely. When she finally received my e-mail and replied, it appeared as if she is so overjoyed. Her words were full of happiness that one would expect of feel having found a long lost friend, and she said she would contact me later that day. Since we live in opposite sides of the earth, it was evening and then night for me. I killed my sleep and waited for her message/e-mail the full night, but no message whatsoever. I started fearing if everything is fine (yeah sorry for the paranoid nature of mine..), and later the next day evening, I got a message saying that she had been busy that day and went to sleep as soon as he came home..and sounded quite casual. So, my question is, how can I understand what was on her mind? Was she just toying around with me? Being extremely happy one moment and sounding pretty casual the other, I just don't understand..

Girls, could you please tell me what this means? Guys' opinions are welcome too..

Analyzing girls' behavior is sometimes very difficult...

Thank you for reading (and many more thanks if you decide to help!),

Absolution85