I just got this macbook air a couple months ago now, and about a month ago I saw these dots at the bottom of the screen just above the 'Macbook Air' logo (only visible on lighter backgrounds, but grey as well). It's four tiny dots clumped together. This morning when I opened the MacBook it wasn't there, but gradually they appeared one by one. Any idea what it is? It's hard to photograph - much brighter and noticeable in person.