Your onto something here, OP - have you tried to isolate if it happens with doors locked/unlocked?I'm wondering if the door switch circuit and timer have anything to do with this issue....
Reason is asked previously about a disk being in, ours would spool up , on its own. I could hear it, didnt phase the rest of the family. Went in under warranty, they didnt find anything but it never occured again. Go figure.