While it is not obviously causing any problems, I recently (several zypper dup
ago, I'm currently on 20190514) started getting the following errors in my logs
during boot:

> systemd-tmpfiles[962]: [/usr/lib/tmpfiles.d/gdm.conf:1] Unknown modifiers in command '+d'
> systemd-tmpfiles[962]: [/usr/lib/tmpfiles.d/gdm.conf:2] Unknown modifiers in command '+d'
> systemd-tmpfiles[962]: [/usr/lib/tmpfiles.d/gdm.conf:3] Unknown modifiers in command '+d'

>From a quick look at
  /usr/lib/tmpfiles.d/gdm.conf
and
  https://www.freedesktop.org/software/systemd/man/tmpfiles.d.html
my guess is the prepended '+' is a typo and should be removed.