A further note:

In looking at the problem some more, I notice that certain tracks in the sound edit remain in sync while others float in and out. In other words: I've got interview audio followed by ambient noise in tracks 1 & 2, and in 3 & 4 I've got music audio. The music audio remains in sync, and the interview audio is also in sync, but the ambient noise following the interview in 1 & 2 is out of sync by a quite a bit. Later on in the same tracks (1 & 2), when new audio picks up, it gets back in sync. I've checked the original audio files in the FCP timeline, and there is no sync problem there. What in the world? And thanks for the help,

Chris