There's a calm that comes over you at the airport. I think it stems from the fact that there's nothing more you can do. As long as you have your ticket and your identification, you're getting on the airplane. If you forgot something, toothpaste, a shirt, your favorite green underwear, oh well. You can't do anything about it now.
Now all you can do is wait. Wait in the security line, wait at the gate, wait to take off. You can play on some sort of electronic device, or read, or just stare off into the distance, but all you can do, you've done.
Considering I'm kind of a last minute packer, and things can get pretty stressful, I welcome the airport calm.
I realized on Wednesday that a significant part of the calm might actually be exhaustion. I went to bed after 11pm and woke up sometime between 4am and 5am, unable to sleep any more. And sleeping on airplanes is so comfortable.