I have a similar problem where when I open and unlock my MBP (late 2012 w/ 15" Retina).. 5 seconds later the screen goes black and its locked again. I can unloc

I have a similar problem where when I open and unlock my MBP (late 2012 w/ 15" Retina).. 5 seconds later the screen goes black and its locked again. I can unlock again no problem, but its a bit annoying