title: Getting "Error validating access token" from Facebook for some users
body: <p>I'm getting the following error from Facebook when trying to post to a users stream.</p>
  
  <p><code>Error validating access token: The session has been invalidated because the user has changed the password or because auth.expireSession was called.</code></p>
  
  <p>The workflow is as follows:</p>
  
  <ol>
  <li><p>Authorize with Facebook requesting <code>scope=offline_access,publish_stream</code> permissions (if the current user has not already authorized)</p></li>
  <li><p>Do some work on the server (takes 5-10 minutes)</p></li>
  <li><p>Attempt to publish to the user's Facebook stream</p></li>
  </ol>
  
  <p>This code works for many users, but for some users, I get the <code>Error validating access token</code> error. It started frequently happening a few weeks ago, then seemed to stop, and now happen a lot again. I'm certainly not calling <code>auth.expireSession</code> on my end, and it seems unlikely that multiple users would be changing their password in the 5-10 minute window from authorizing to publishing. Does anyone know what might be causing this?</p>