I’ve seen this before and I saw it again. People’s faces change even before they come home. For some reason, most Russians tend to have this hard look on their face and an absolute absense of smile, unless, of course, they see something funny. People can enjoy walking down the street, but the moment they get to the Russian Embassy, they change. The same happened in the Larnaca airport. People were coming relaxed and rested from their vacations, but the moment they queued up for flight registration, their faces were changing.
Needless to say, when I came to Moscow, everyone had a wooden face. I’ve been to several cities across the country, and the faces were almost the same everywhere. Moscow faces were a tiny bit more serious than everywhere else, but there was no huge difference anyway.