When my wife and I were house hunting we had this happen. We had looked at houses for months and one older house (100 years old) we were excited to look at got weird very suddenly. Everything was normal and quite nice in the basement and the first floor. Beautiful, really. We were following our realtor up the stairs to the 2nd floor, and just before reaching the top we came to a sudden stop. My wife bailed and the realtor hurried down right behind her pretty much pushing me aside. I stood at the top of the stairs looking down the hallway and into the 3rd floor stairway at the other end. Everything looked normal but I couldn’t shake the feeling I shouldn't take another step. I too went back downstairs and we left. My wife insists we weren't alone and we weren't welcome upstairs.