Hmm, idk. I feel like Katie merely told Aiden loosely about the tape she saw with her friends, she doesn't give any indication of walking around in fear. I'd assume that aside from the occasional nightmare and absentmindedly scribbling out people's faces, she probably wasn't super absorbed by it.
Even when relaying the news to Becca, she goes back into joking around.

Okay. Thanks.

People who are cursed by the tape possess the foreknowledge of how much days they have left until their deaths. It didn't really matter what day she told Aidan about this but she mostly like confided him with this since everyone else would think she's crazy and Aidan has special psychic abilities. Samara's victims are taunted by the short amount of time they have left through visions which usually intensify when the time limit reaches to the end.