About a week ago a Yamask decided to catch himself in one of my spare pokeballs. I was planning on keeping him, but a superstitious friend of mine is really freaked out by this. My friend says that only ghost types that knew you in a past life would let itself be captured like that, but I don’t think I’ve ever met someone like this Yamask before, living or dead! The face on his mask doesn’t look familiar either… Should I be concerned about this?

Not really, anonymous. Unless you managed to make quite a few enemies. At which point probably.

In all seriousness, so long as your yamask is friendly towards you, there really shouldn’t be any reason to worry. There’s a possibility that it remembers who it was and is trying to resume that relationship with you, but if that’s the case, then there really isn’t anything wrong with that—again, unless you can recall anyone in particular who exhibited rather worrying behavior towards you.