Disappearing and reappearing pen

This happened at the store we own and operate in a building that was built in the 1840's in a very small Ohio town. The building was built as a General Merchantile but fairly quickly became a hardware store and served as such until the 1980's when it sat empty for a while and then served several owners of miscellaneous shops until the turn of the 21st century. We took over the store and its present business (home décor and notions)around 2011. Today, my wife was working on store papers in the main show room, she was using a bright green pen. This was early and no customers had, as yet, arrived. The table sits about midway in the main show room. My wife is confined to a wheel chair with minimum walking with a walker. She hadn't been out of the wheel chair all morning. I was working at the cash register on the far side of the store next to the entrance. My wife had just finished a report and laid the pen on the table while she proof read her report. She finished reading and went to pick up the pen, but it wasn't there. It hadn't fallen into her lap. It was not on the floor. Had it rolled anywhere on that table it would really stand out. So I brought her another pen (also bright green) from our desk behind the cash register. She continued making her corrections to the report and making checks out to the utilities. Probably close to a half hour later she let out a surprise cry, and said, "Look here!" That first bright green pen had suddenly reappeared on the table. There is absolutely no was the two of us could have missed it when we searched for it. This is the kind of thing that makes you think, "Perhaps I have a ghost". Other explanations are more than welcome.