I'm not an expert on dogs, but dogs are generally not wired like that. Even if he is generally a calm dog, wouldn't he be in a frenzy or at least go out to see who is coming in the middle of the night if it's an unrecognized smell? Even if it is recognized? As a matter of fact, the dog thing is curious because I have heard nothing about it. Where was the dog anyway? First floor? My dogs used to bark like crazy at known or unknown people and knew me coming in to my apartment from the minute I used the elevator. Obviously not every dog is the same but dogs generally are inquisitive creatures like that - they'll try and alert their owners in some way. It's curious we have heard nothing about the dog (or at least I haven't).