Why does she text me like this? Girls opinions?

This girl who I've been talking to for about a month now is confusing me recently. She always texts first, compliments me, etc, etc. We've hung out a few times and it was great. We've basically said we like each other, and we're just waiting for the right moment to start a relationship. But lately, for about a week now, she's been texting me weirdly. Like I understand people have things to do, and I'm fine with that, I don't need to be texting her constantly, but she'll text me, and we'll be talking for 30 minutes. Then it'll take her an hour to respond to one message. Or she'll text me at the end of the day, then I'll text back and not get a response. Then the next day she'll text me saying sorry I fell asleep etc, etc. It's just little things like that that are my pet peeves. If you don't want to talk to me, don't. If I was texting her and this was happening, I would think she was losing interest in me. But she's texting me first, saying we need to hang out, and making the effort with everything. I told my best girl friend about this, and she said it just bugs me because I like her so much. From a girls' perspective, do you think I'm over reacting? If you were doing this, what would be the reason? I just like her a lot, so I'm thinking to into it I think. Thanks for the help.