Problem solved by removing the three touching keys and installing them back. No more touching or sticking at the lower edge.
I've purchased my laptop way back December 2015, but I've just noticed this problem only now when I was working with excel. When typing fast with lowest three keyboard buttons, especially when you hit the lower edge of the buttons, the keys will hit the edge of the hole and it is very annoying. Seems like these three keys are very close to the edge of the hole.
Can other G752 owners verify this on their unit? I seldom use these keys in games. I mostly use wasd and mouse for games, but when I used excel, I began to notice my problem. It is very annoying. Is there a way to fix this physically? If not then I must practice to typing dead center or on the upper part of these keys.