I have the rMBP base model and the brightness continually is adjusting on its own, even though I have NOT checked the box "Automatically adjust brightness." For example, last night I set brightness to maximum and then when I checked this morning it was at about 85%. I did nothing to change this setting and both times the rMBP was plugged in. Is there something that is wrong with my system or is this normal behavior (and if so, can it be disabled)?