He's not hoping it's John. He's absolutely not crossing his fingers and wishing that John's showed up at his door like thinking hard enough about him has somehow brought the man here.
Q tugs off his cardigan and tie and untucks his shirt in an attempt to less workish and more casual and cool. Or as casual and cool as Q is ever able to get. Just in case it might be John. But if it's not, that's completely fine.
But it is and Q breaks into a grin taking the cigarette from between John's lips and kissing his cheek before stealing a drag of the cigarette. "Hello then, you."