Key popped out from my new X1C3 2015 :(
natalian.org/archives/2015/02/18/Archlinux_on_a_Lenovo_X1C3/
Update: After a lengthy back and forth with Lenovo, they said basically that's it's not a problem and they will not replace the keyboard. Therefore I will be dissuading anyone to buy a Thinkpad from this point on.