For the last few months my rMBP will sometimes make a strange sound. I finally got two videos of it. It's tough to hear so you might need to turn up your volume. It has a constant pitch. To me it sounds louder from the left side of the computer than the right. I can't recreate it at will it just happens. Also, starting last night the battery won't always charge. It's plugged in with no light on and the battery menu says it isn't charging, but the charger is powering the computer. Strangely, if I unplug it from the computer and plug it back in the light comes on and it charges. I don't think the battery having 1,384 cycles is doing much good Currently, I'm finding that unplugging and plugging it back in with the computer awake or the lid closed and asleep, it's charging fine. It's only happened twice where it doesn't charge. Once last night and once this morning. Overall the sound is more concerning to me.