Is it normal to feel very easily overstimulated in loud, crowded rooms?

I just attended a loud and crowded information fair. I am a confident and social person by nature, but, to my dismay, I started feeling very claustrophobic and nervous. I had the strange sensation that I couldn't focus on anything, because my mind was too busy trying to attend to the (many) small details, noises, and motions in the room. It disturbed me, because I never feel like this. Is it normal?