It seems SF login sessions times out  when suing https://workbench.developerforce.com/ in about 10-15 minutes.  I have the org session timeout set to four hours.

Anyone know why the session dies so quickly in workbench?

It's rather annoying because I could be working on a query and have to do some other stuff in another window in a bit and then go back to it.  Then my login is timed-out in the workbench sessions and I get kicked back to the login screen and lose everything I had been working.