The iProducts they are, for the most part, naturally beautiful, but some people like to personalize them with stickers, cases and other accessories. However, MacBook Pro users with a Retina display need to be careful not to put stickers in the wrong place.
According to a notice on the Apple support website, users of this machine must not stick stickers on the inside of the product, or they may damage it.
To allow for a slim design, the space between the screen and the palm rest is designed for small tolerances. Do not use palm rest covers (adhesives in the resting place for the hands) as the added thickness can interfere with the resting position of the fabric.
So no Iron Man stickers or tribal designs where you support your hands. If you have one, it is recommended to take it out immediately.
(via Cult of Mac)