I doubt I still have both before and after grub.cfg
I have no proof at all that grub2-mkconfig after each kernel update is needed. I got this from an old thread [including you Chris Murphy] [And specifically the combo command from Gilboa Davarra] I could easily have misinterpreted it.
I did have 2 recent cases so far that grub2-install was needed after kernel update. $ uname -r 3.14.7-200.fc20.x86_64
Jack