iMac 27" dark stains inside the screen

iMac 27", purchased at 16th April 2013, so, one year later without guarantee, and dark stains has appeared inside the screen as you can see in the pictures:

I've googled a lot of forums and youtube videos with a lot of people with the same stains, and it seems its a condensation behind the glass, but my iMac is 27-inch, Late 2012 model, so with the thin iMacs you can't remove the glass to clean the screen, because the glass is glued to the iMac and you cant access to the screen, you have to dismount a lot of pieces to access screen.

So, my question is:

¿Am I screwed?