Could be, but I never had any issues with it for normal usage. It is also super convenient that you can just press it and you are back directly in the application where you were when you locked the device.

No need to activate the screen, swipe away the lockscreen and then select the application to get back to.

BTW, that's really something Sailfish OS needs to improve - you should be able to get back to the last used application instead of being dumped to the home screen every time. It is super annoying at some times.