O.K., so I finally figured it out - files will not reconnect in FCP automatically (or at least the "reconnect files" window won't pop up with only the relevant clips listed) unless you have FCP open at the same time you save your new files. What does this all mean? If you're animating like I am, plugging individual tiff files into a Final Cut timeline, and you want to change the animation along the way or somehow alter the tiff files so that you need to resave them, the cool little reconnect files window won't pop up and allow you to...um, well, reconnect, the necessary files (or plug the new, updated tiffs in). Instead, you have to go do it manually, going into File/Reconnect...and thereafter swimming through an extremely long list of tiffs and jpegs. Do the smart thing (that I eventually figured out): save while you have your file open. You'll be so cool that way.
Final Cut Pro tip of the day: A particularly handy one from my instructor - does your sound have some hideous clicking going on, particularly once you've made a final QuickTime movie in FCP? That's because you put an MP3 sound file in FCP, and FCP hates MP3s. Hates them! Arggh!!! Simply go into ITunes and convert your MP3 into an AIFF. Or spend a ton of money on some other sound file converting program. Your choice.
Have a delicious day.