You're trying to figure out whether you should date her because she lives far away. There are 2 things you should've verified in your conversation:
You did well with #1 by challenging what she says and not always making it easy for her to respond. Her continued positive responses makes it a strong case that she's interested in you.
You could've done better with #2. You talk about liking "challenges" but you weren't specific enough about what you meant. You should've tried figuring out specific qualities/interests about her that you like too. For example, if you're into baseball, you should've mentioned baseball.