Recently while wandering about in the sewers, I've been receiving "your actions make you more liable to expose your presence" while in stealth, and using subsonic's bard song.
When passing some rats, I failed a Move Silently check when I renewed my bardsong, which should not have happened, as "He can play so softly that his opponents do not hear it" but clearly they did, and it broke my stealthy state.
To replicate, use invisibility (I was using imp invisibility, myself) and subsonic'd bardsong near foes.