1. If you were hungry, it is not a ghost and it might be food. Your mind is playing tricks on you with dinner time.
2. Next time walk up to it to see what it really is. I know that curiosity kills the cat but wouldn't you rather know than living the rest of your life, knowing about a lie, that is if it is a lie?
3. Until you factor as much constraints out as possible, lets not conclude so early that it is a ghost. Did you lose your spirit? Were you scared? Are you feeling sick? You need a Shaman to perform a ritual for you?