I think the machine only works when you pull the lever. At any other time, it's completely unaware.
It could also be that the machine KNEW, but had no way of thinking it as a bad thing. And even if it could, it's only actual function is to print paper. What's it going to do, flood the room with little paper slips?
I guess Twilight does have a point, the predictions came true based on what fortunes they saw. And staying around to continously read more fortunes would have caused Applejack and Pinkiepie to neglect their jobs henceforth making their fortunes come true again.
Twilight explains - those probably happened because they were so obsessed with the fortunes that they would probably be there for weeks, reading them (thus ruining business for Sugarcube Corner/Sweet Apple Acres). After their epiphany, this will no longer happen. The machine only predicted it in the first place because it never expected to be destroyed, as Twilight also explains.
You should, you should! The Twilight Zone is one of the best not-so-horror-esque television series from the 60's -- some of them are even quite light-hearted and funny But you'll need to prepare yourself from some of the more scary or sad ones; they get me all the time.
How long does it usually take you to make a comic like this? I'm trying to do my own stuff and it takes AGES. I really love your comics, though, and I feel like you do so SO much more work than I can do.