Hello Kubla,
As you know, I am a past Acoustat III owmer and on a couple of occasions a similar phenomenon occurred -- but only with one recording. I was playing through the tracks on Madonna's "Immaculate Collection" CD and I started to play the song "Vogue". As the song progressed, I distinctly heard Madonna's breathy voice whispering "Vogue" distinctly inside my left ear. So, if you too were listening to that particular song when this occurred, I think that simply reversing the left and right channels will set things right again. --Either that, or say 10 "Hail Mary's" and 5 "Our Fathers," then make a sincere "Act of Contrition". The latter option seemed to work best in my particular case.