Strange reactions from our dog

     I have said several times that strange activity occurs in this house usually after election day each year. So far this year, the house has been exceptionly quiet since the November elections. The single possible exception to this occurred last night. Having retired for the night, I was engaged in a romp with my dog, as we usually do, for twenty or thirty minutes before I bed him down for the night. He  really gets into the play. But mid play, last night, he suddenly stopped and stared down the upstairs hall. Thinking it a momentary thing I again engaged him in rough housing which he, for a moment, returned to; but again, suddenly, he stopped and again begin starring intently down the darkened hall, low growls issuing from deep in his throat. My wife asked me if I was sure I had locked the back door. I replied that I was. She was quick to point out that nothing short of an earthquake would deter our dog from playing. So I said I'd check the house out and see if we could determine what got the dogs dander up. Normally the dog will playfully preceed me when I'm going anywhere about the house; but this time he stayed in the bedroom until I turned on the backstairway lights which are a ways down the upstairs hallway. As I decended the stairs I could hear him coming, I was at the midlanding when he appeared at the head of the stairs but he proceeded no further. I went on downstairs, checked the exterior doors and found them suitably locked. As I passed the stairs on my way to checkout the diningroom, I looked back up the stairs to see my dog standing at the mid landing of the stairs; he made no attempt to come on down (most unusual). I checked out the downstairs rooms and front door. I found nothing that should have upset him. I went back upstairs, the dog now preceeding me, put himself to bed (also rather unusual). While I can't say there was anything paranormal about this episode, it was strange all the same.