Namerovsky made a phone call. At 3 AM, I suddenly heard a loud dial tone, and then a number being dialed rapidly. Then I heard B.B. Av jump up and say, "Oh no, Kitty, it is way too late to be calling people." Namerovsky, while exploring, had activated the speaker phone and stepped on a speed dial button. Who he called: B.B. Av's father, for unknown reasons.
XE got it right and he is somehow slipping under the inch crack under the door. But I haven't seen it or heard it. Often, he slips in without me noticing - whatever he does doesn't make noise. You don't hear anything around the super sensitive hollow metal door. He's just in.