Putting Matte on Alters Music Levels

Hi - just put a widescreen matte filter over my entire cut (nested) and for some reason, in ONE spot, it affected my music levels. Made them jump. I had keyframed the audio to bring down a music swell. There is no music cut at that point, and the level bumps up and then down NOT at a keyframe.

This only happens when I put the matte on. I've trashed prefs and tried putting on the matte with locked audio tracks. Putting on the matte with locked audio tracks worked in the sequence, but when I exported to Quicktime (7.4.1), the problem was there again.

Any ideas??

is the music at 48khz?