As she listened to the surprise new record 'folklore', the 28-year-old star shared a screenshot on Instagram Stories of the track 'cardigan' and wrote: "She's done it again @taylorswift."
Meanwhile, Taylor, 30, admitted she didn't even tell her friends she was working on the album, which she released less than 24 hours after announcing its existence.
Speaking in a fan question and answer session, she said: "No one knew I was making an album. I didn't even tell my friends until right before announce. It was my own secret world I'd go to and I've never made music like that before."
And Aaron Dessner - who worked with Taylor on 11 of the tracks from the new album - even kept it a secret from his daughter.
Aaron shared to Apple Music: "I was so glad that we kept it [a secret] because I didn't want to be the one that spilled the beans. Because even like not telling like even my daughter ... I have an eight-year-old daughter and one day she asked me. She's just like, 'Daddy, do you know Taylor Swift?' It was the morning after we'd written like one of these songs. And every time we would write a song, it was like a weird lightning bolt, getting this struck by lightning or something and just like exhilarated with electricity. I just looked her straight in the eye and said, 'No.'"
Taylor explained via Instagram that she hadn't actually planned to release her new album at this time, but recent events have reminded her that "nothing is guaranteed" in life.
She wrote: "Before this year I probably would've overthought when to release this music at the 'perfect' time, but the times we're living in keep reminding me that nothing is guaranteed. My gut is telling me that if you make something you love, you should just put it out into the world. That's the side of uncertainty I can get on board with. Love you guys so much [love heart emoji] (sic)"