Is it normal to get nervous around my boyfriend?

We've been together since the beginning of the year, we're both in high school, and he's my first love. We know so much about each other, and he's also my best friend. He's extremely respectful and sweet and romantic, and most of the time I feel very comfortable around him. But sometimes, I get very, very nervous. I can't even explain it, it's just like, if he's wearing a really nice shirt, or he does something really cool, I suddenly feel like a stupid girl with a giant crush and stutter and my thoughts scatter! Even sometimes when I just get lost in his eyes, I suddenly get embarrassed flustered and awkward! I know I love him, and he loves me, but is this normal? If not, how do I get over it?