Your not crazy...and forget that word Crazy, Everything exist from Paranormal to unknown fiction creatures, you have to believe in it and send your energy to make it exist.. and with Ghosts if your scared and you showing them they going to feed with your " scariness ".

If it never happened after this experience then forget it. If it happens again maybe you have a Lost spirit or something else trying to communicate. If your really Scared go to the church ask them to purify your apartment.