Yeah - Idon't know if this has happened to anyone else before, but I used to have a Tascam 464 - after a year or two of not demagnaitzing it, it started to pick up radio stations, you would hear a radio being played very faintly on every track-you would especialy hear it at the end of a recoding after it out faded out or stopped or whatever - (music)La la la la- "...and today will be bright and sunny with a high of 87 degrees...".
And if I remember right, the demagnatizing cut down on it considerably - unless it was some other reason - but that was so long ago.