Default [Q] knock off

Guys I am having a little ...you can not say it a issue but a strange thing which i experienced few hours ago. two days ago i returned back to stock on my lg g pro from V5.But a few hours ago i noticed that double tapping on screen make it off.I cant understand why is it happening.I flashed F240L V10z.kdz. But i also have flashed thunder kernel on V5 rom. Is the kernel causing the screen to turn off. but when i flashed kernel i was able to turn it on by double tap not off.But now i am able to turn it off not on.Can someone clear me what is causing this????