Premiere 15.0.2 (Build 35) on Windows...

When adding an audio track on the timeline (right click on audio track's head on the timeline, select "Add Track") the associated channel in the Audio Mixer can become mislabeled. For instance, if you add a track below track A3, TWO tracks labeled "A3" will appear in the mixer and all tracks afterward will be off by one number... i.e. A5 in the timeline is actually labeled A4 on the mixer.