facebook/php-sdk — comment on commit 2b19d803635b36d0ad06faac4e253c83dcbf68aa
File:  line 0
By gstasica:

I don't think so, unless properly clearing up the session and logging out operations are not related.
If the user clicks logout link (url obtained by a call $facebook-getLogoutUrl() ) than any subsequent calls to $facebook->getUser() method call should return 0 value.
In my test (see my earlier steps to reproduce) $fb->getUser() method call returns my userId, even though i've already logged out (clicked logout link)..

i hope i make myself clear