How do you feel or act when someone has revealed to you that they have a Crush on you?

Just last night, I have a Friend that is a Girl, just told me last night that she has a Crush on me. Honestly, I don't know how to feel about it, even though I am Flattered about it as well. The only time a girl has had a Crush on me was many years ago but I never thought it was possible for someone telling me something like this before. Is this normal? How can I deal with it?