Phantom Dog ot ?

Last night I had a strange experience. I had just sit down to the computer intending to read some E mail. It must have been about 7 o'clock pm. About the time I started reading, my little schnauzer, Shadow, came into the room and wanted me to pick her up. I picked her up and she did her typical turn around on my lap before she settled down. My wife was working upstairs and we have no other animals in the house at this time. I had just resumed reading my E mail when I heard a distinctive thump like something hitting the floor behind me. Immediately I heard the jingle of what sounded like dog tags jingling on a dog collar. I turned in my seat, but saw nothing that would have made that sound , nothing out of the ordinary. Shadow did not react. I hesitate to bring this up; but I recently (about 11 months ago) lost a little male schnauzer named Rowdy. That chair in the library was his favorite. I know it seems a bit far fetched. On the other hand I have no logical explanation.