Blade Base 15 screen blanks when pushed back to extent

Hi, i just got a blade base 15. When i push the screen backwards, jut before it stops at the limit (about 120 degrees) the screen blanks. if i pull it forward the screen is restored. I have never seen a laptop do this before, is it normal for this model or is it a fault? I just want to know if I need to start an RMA. I notice this because i use the laptop on a tilted stand so to get the monitor vertical i have it past 90 degrees.
thank you!
Michael.