NightDude, NightDog and I live in the basement suite of a house in a quiet smalltown neighbourhood, and NightDude is out for the evening. NightDog is a really relaxed, goofy lab-mutt, but he's been incredibly agitated all evening. Normally he flops down on the floor of whatever room I'm in, but for the past couple hours he's refused to enter the far section (bedroom, office, bathroom) of our apartment. If I call him from one of those rooms, he'll come over slowly with his head down and ears back (very uncommon body language) and shove himself between my legs. If I move at all, he leaves immediately and lays by the front door. I've taken him out several times, thinking he might be ill, but he seems totally happy and normal as soon as we're outside.
So... there's a serial killer hiding somewhere in my apartment, right? Honestly, I've become so paranoid that this has started to seem like the only solution. I've gone through every cupboard and looked under the bed and there's (obviously) no one here, but I'm still freaked out. Reassure me! Is this normal dog behaviour?