I think it's too early to say 1989 doesn't include any country song, it's reasonable for her to label 1989 as pop album, because it's necessary and smart for her to categorize the album, especially while promoting such song as "Shake It Off"
Edit: I bet there's still country song or at least country influenced song

on 1989.
Edit2: As you all know, NONE of her albums only stick to one genre, even including her debut.