invented to keep out the cold
Well, first, she knows she is to keep this secret from Mother. ...does she? Mother told her that last time she awoke from death, but if this is malicious that could have been a lie. Her only confirmation of the vision (memories?) comes from the second time around, and right now that has to be suspect. If she were tricking someone like this, a false illusion of the future followed by another illusory future apparently confirming the first would obviously work without requiring the true world to ever back her claims.
She feels inside herself, and... yes, there's Prestidigitation. If this is a lie, it's a lie constructed at a perfect moment, just as her sorcery was coming in. Or someone found a way to implant new spells in a sorcerer, and used it on her to apparently confirm this. Is that possible? Maybe. If it is, it's not cheap. Sorcerers mostly don't know all the wizard cantrips, or even the ones they want to learn. If just any strong wizard could do that, it would be for sale.
So, then, the possibilities: someone spent quite a lot on her and did something she's never heard of to make these memory-visions look believable, they're true prophecy of some sort, or someone just picked a perfect moment to catch her, knew she was gaining Prestidigitation, and can implant accelerated visions somehow. Her death, if it is to be believed, happened when someone took over her body and used it to cast their own teleportation spell, she felt that casting unfold from a scaffold she had never seen before. She can't hold the shape in her mind, and she couldn't power it anyway, but if these were true visions then someone was casting through her body. Is that possible? Domination uses your victim's own power... possession might do it. Ghosts are supposed to be able to possess people, and maybe they can cast their own spells from inside. That's not unheard-of magic, then.