It can just as often go the other way, the selector takes excessive force to move.
The detent is machined to a point, and sometimes this can be too sharp. It will round off with use and become smoother, or you can speed up the process and hit the tip with a diamond file.
Sometimes there is too much tension from the spring, and trimming off a coil or two can help.
No matter whether the problem is too stiff or too mushy, you must be careful that when you put on the grip that you don't crimp or pinch the spring. Do not slid the grip on haphazardly, but straight up.