Facebook Page Access Tokens - Do these expire?

I'm building an app that allows users to administrate their Facebook Fan Pages. This requires the following two Access Tokens:

Facebook authentication error - The operation couldn’t be completed

I have an option in my game for users to post an achievement to their wall. If they are logged in, i.e. their token is still active, it works fine. However, if they need to renew their token, the app exits and the Facebook authentication page loads for a second before returning to the app (they only need to click OK on the authentication page if they have actively logged out, otherwise it happens automatically).