It seems to me in this case, Earl wasn't being too realistic. You've been talking for about ten minutes. You're interested in her, but you're not quite sure if she's interested in you. This is a very important factor in determining a girl's interest. But just because she's answering the questions doesn't mean she's interested in you.
Rapport is of crucial importance.
You think you want to ask her out. Check your status on the above pointers before asking her out. You could be the most fantastic and appropriate person on earth, yet rejected, for a reason none other than bad timing. It's important to realize that being rejected is sometimes not at all your fault, and is not due to any sort of character deficiency on your part. Or maybe she just wasn't interested in you.