Login timeout?

Does anyone else have an issue with the user ID timing out? I had started a thread this evening and while I was searching for information in another window to complete my post, my login timed out and I had to login again. It was a short time also, less than 15 minutes.

Luckily, all the info I had put in my thread start was not lost so it was only a minor inconvenience, but this is not the first time this had happened to me. I reviewed all my settings in the CP, but nothing stood out.

Is it only me?