Why is this girl ignoring my texts?

We started talking on a dating site (meetme) a couple days ago, and she seemed really interested, and we exchanged numbers. Then while texting, we decide meet next day, and she says she'd love me see her bed. And then we started talking bout sex, sexting, etc, etc. But the next day I text her and she doesn't respond so I wait 4 hours and try again still no response. At night though I go on site and find out she had logged off four minutes before I got on, via phone. And one of her posts was "I can't believe I just did that". What went wrong?