TMF friends tell me, why would a female text you first, then you text back about 10 minutes later and get no reply for the rest of the day, when she is the one who started the conversation?...smh
Was it a yes or no question? Or, an open-ended question? Do you always reply exactly ten minutes after the question was texted to you? Is this a girl you are interested in, or just a friend?
She's not that into you and she simply wanted some attention. She got it, and something more important came up. Don't take it personally. Keep busy/find another girl.
There are a thousand reasons why she would do this. You'll drive yourself crazy over analyzing it so just be cool. She'll get back to you if shes interested