W541: soft minus key at the numpad

[AKazak]

Greetings, dear community!

I have a brand new W541, but recently noticed that soft minus key at the numpad is much more soft than all other keys of the keyboard.

http://cloud.screenpresso.com/AH1Mf/cne ... allery.jpg

I want to understand what it is: bug (flaw) or feature?
Can you try reproducing this please?

Thank you.