I noticed then when using the facebook login, and the browser is closed, you are immediately signed out and you need to login again. I suspect that FBConnect does not save the sessions cookie with the proper "remember me" time-out setting.
I looked into the code, but was not able to find it.
I suspect that in:
/ow_system_plugins/base/bol/user_service.php
The funtion:
public function processSignIn( $identity, $password, $rememberMe = false )
Is called, but with $remember me, set to false.
However I could not find this call in the FBConnect plugin, so I cannot verify this. I tried setting it default to TRUE, in this line of code, but that did not do it.