I often use my iPhone 3GS to play some music before bed. I start the music, set the timer for 10 mins with an action of Sleep iPod, and it happily shuts off. Last night was of course the first time doing this with iOS4. After the music finished (and I was just about asleep) a beacon of light entered the room. That was the iPhone screen displaying "Timer Done." Is there a setting I'm missing somewhere? It didn't do this before, I don't believe..