Unusual Intruder

My wife had quite an experience today. But thats what she gets for skipping church today. I will write here just as it happened. I will make comments in parenthesis. Otherwise in her words:Quote, " While washing my hair, it sounded like the door to the parlour opened. (the door is very heavy walnut and the antique hardware makes a loud noise when engaged) Both dogs barked, so I grabbed a towel and went to check. Shadow (our younger dog) was sniffing at the base of the door and growling like crazy. Roo (her pet name for the older dog) was also sniffing at the door and barking (the door was shut). I went into the Parlour (without the dogs) through it to the hall and front door which was locked with deadbolt in place. I found nothing amiss. I came back through and went back to finish my hair. Shadow continued to sniff at the door and then at the foot of the rear stairs(there is a gate in place there to keep the dogs downstairs during the day). Roo barked at the backstairs. I went up the rear stairs and walked through the upstairs. Before I got to the master bedroom , both dogs were angrily barking at the parlour door (they must have been loud to be heard upstairs). I hurried through the master bedroom and into the upstairs hall and down the front steps. Everything seemed fine. When I reentered the diningroom though the parlour door both dogs were still barking and Roo's hackels were standing up. Both dogs continued to be agitated and restless" unquote. By the time I got home about 11:30 am they had settled down. I went all through the house and found everything to be in good order. I have no idea what my wife and dogs heard. I think, though, if it were to happen to me, I would have opened the parlour door and let the dogs go in. If it were physical they would have run it to ground, if it were something else; I'm quite sure they would have hightailed it back to the kitchen. They have done that before.