It seems that when it gets close to Halloween here, there's a weakening of the barriers between life and death, and reality and dreams... and between this castle and the rest of the world outside it, though I wouldn't recommend testing that by trying to escape.

The ghosts you might have seen around the graveyard in the new area are apparently actually monsters that got in from outside the castle, because the barrier is weakened right now. They're likely to speak to you and try to scare you, by the way, and they're not confined to that one floor, so... please be aware of all of that.

This may also explain why those who have supernatural abilities are able to use them again, in which case that's likely also temporary.