I have recorded a song that contains loops, midi drums and keyboard, electric gtr, electric bass, several different lead voc tracks and also 6 background voc tracks. Project tempo was 112. I have found the song was recorded too slow. I tried varispeed but even going up 2%-well, I can hear sonic degradation and so I have decided to keep my midi and loop tracks-bump the track BPM up to 115 and retrack the recorded audio (Vocs, gtr & bass). As expected guitars-bass and most of the vocals were totally out of whack/too slow when I bumped the meter up from 112 to 115 for the new version of this song. No worries-I expected this and will simply retrack. BUT>To my surprise the several lead voc tracks have switched tempos and sit perfectly in time with the track and sound natural-no artifacts that i can hear--WOW!!!! This is a bonus. BUT-why would these couple tracks migrate to the new tempo and not others...what is going on...?...