Ghost chess player

When i was about 10 years old me and my sister were playing a game of chess on a completely glass chess board. When the game was about to end with my sister wining i decided to just make my king try and run from my sisters pieces instead of win kinda to annoy her. Our mom came over to try and see if she could help me win, (i was young and new to chess). When my mom moved the king to one space it seemingly moved back, we all were very confused so i moved it back to the space it was at but it moved back again. To this day we don't know what it was, we checked and we physically couldn't make that chess piece move the same way it did that day.