This may be the correct behavior depending on how you set the extension. Go to the extension and then the office hours scheduling tab. There you will find an option to select how you want the "Q" availability to be based upon your availability.
A Q is different from the normal call handling. They give you the option as you may be in a Q and still want to take normal calls as well as Q calls. On the other hand, perhaps you need to be in the Q and can't be bothered by normal calls. You can then set your status to away and force normal calls into the other call handling options you set, but still be able to take Q calls. Otherwise, if you want the opposite - take normal, but not Q calls, then log-out of the Q.