During the series, Saki often sees really weird visions, sometimes very phantasmagorical. If I remember correctly, first time was when she was trapped with Satoru after encountering hostile bakenezumi.
So, to put it short - what was actually source of her visions? It's clearly not normal for human to see things out of nowhere. I may understand why she is seeing visions after
Shun becomes Karma-demon (may be impact of his power on her brain/subconsciousness or something),
but not for first time at least.