That doesn't really discount it being Mion's, does it? She could've gotten it just like you have. [ ...erm, this is probably a bad time to admit to this, but-- ]

I've gotten a handful of weapons from the machine too, but I don't know what to do with any of them, so I just leave them in my trunk most of the time. [ Don't come to his room for a murder weapon it's always locked. ] She might've been the same way or something.