She probably doesnt notice. Usually the reason why you stutter or mumble when your around someone you like is because your thinking about the way your acting too much. Just relax.
She'll think its cute. It's a compliment to a girl when a guy blushes or fidgets when he talks to me. Plus it will show that your a nice guy and genuinally (however u spell tht) care.
I have noticed it, guys have done it to me. It doesnt bother me at all. I think its cute, because I don't understand why they would be nervous i dont care. haha but yeah just be calm dont worry about it. The girl is probably a little nervous too
Don't worry about it-I'm in high school and I'm the exact same way, and I even lose words. Like this girl I really like (I think she likes me), she asks me all these questions and I just say a few things and then I'm like "I dunno" and I feel like a complete goof. But usually if I can calm myself down-then I'm ok.
turning red around her 
