I guess it's like there is some physical proof out there of their relationship (in that paper trail), and on that piece of paper.
It's a while since I read the story, but I just pulled out my copy of the book and read the first section again, and now I've seen it, that line does jump out at me. It's a kind of hint of what's to come. Like you say it's as though even before they met they were fated to be together somehow.
After your earlier post I had to stick the DVD on again and watch that scene (even though I watched it last night). Again, I've never paid that much notice of the scene in Agguire's office, but yeah, the paper in Agguire's trash can sums up Agguire's view of their relationship all the way through and so much more.