Vostro 3500, screen burns in

I have a Dell Vostro 15 3000 (I bought it approximately 2 months ago). In the last few days I noticed that anything on the screen left there for a longer time burns in the screen. It can be seen mostly when the background is grey as you can see in the image I attached. I had to take that picture with my phone because a simple print screen doesn't show the "burned in" parts, so that's why I think that this is not a software problem. Did anybody else met with these kind of problems? If yes, can you help me what to do?