Is your house haunted?
I only ask because Sergeant and I went to our property in WV last weekend, it was my great grandparents house that they built about 100 yrs ago, Its deeply rooted to my whole family and its very haunted. Sergeant was being soooo weird about it. he would walk up to a door way (that no longer has a door attached) and stand up on his hind legs like he was trapped behind an invisible door and was leaning against it with his front legs.
He was also digging at the stairs a lot, barking at the rocking chair... all kinds of weird stuff. He never acts like this at home, so I know its not a weird neurological thing.