Q: Can hot pixels (bright spots defect) spread?

I just noticed that my Macbook Air 11" (bought october 2014) has three spots of hot pixels.

Those pixels are always on, brighter and more noticeable when the screen is white (see http://en.wikipedia.org/wiki/ISO_13406-2).

There's not way to see them when you're directly facing the screen, so they're not a real problem.

Therefore, I just wanted to know if the "bright spots defect" can spread to other pixels.

Furthermore, is there anything to do about it? Can they disappear over time?

Thanks for the help.