Some great comments in here already. And to add to it, just reverse the situation and imagine what she's thinking. She won't want to ask you about it unless you mention it. So, tell her you were nervous and explain why. Not only will it help calm your nerves, but it's a great way to show you're an honest guy who can talk about deep stuff. And remember the most important thing is that you're in the same spot as every other guy. Everyone gets nervous. Be honest and if she's the right girl for you, you'll know. If she's not, then that's her loss. At least she saw the real you.