You didn't run heavy tasks like gaming or video editing, 4k video watching, 3D/sound rendering for a week or so? Fans are running only on lowest speeds for a while? My advice: Let the fans run on maximum speed for a minute or so at least once a week. It will blow through all the nearby hardware components and some dust and other small particles will leave your device. Do the "rush through task" immediately after you hoovered your room and cleaned your desk for being sure that you don't push even more dust into the device. Seriously you can take it into your (dry and clean, tiled) bathroom because it's always the room with less dust. No smoking during the task. To accomplish this you don't need to open your device but download and install the free tool SmcFanControl (donationware, needs 10.5 or newer; source code @ github.com) and max out the settings for both fans. (Tested on rMBP. Read the FAQ. I am not the dev—just passing the info.) The setting "max" is not provided by default so you have to add and save it manually as shown in the screenshots. Edit: Okay nothing is as completely and thoroughly and efficiently than taking the device apart (you'll need some special tools—for the rMBP—and skills and take care of the warranty) but the "software solution" is clearly "better than nothing" and the life span of the device will be extended.