My user isn't part of the sudoer's file either. I ran today's journal and didn't see anything, so I looked in the whole journal, and, interesting enough, this is what popped up.
$ journalctl | grep hddtemp
Feb 17 14:36:29 siduction64kdefx sudo[18685]: goineasy9 : command not allowed ; TTY=pts/2 ; PWD=/home/goineasy9 ; USER=root ; COMMAND=/usr/sbin/hddtemp -nq -u C /dev/sda
Feb 17 14:36:29 siduction64kdefx sudo[18702]: goineasy9 : command not allowed ; TTY=pts/2 ; PWD=/home/goineasy9 ; USER=root ; COMMAND=/usr/sbin/hddtemp -nq -u C /dev/sdb
Feb 17 14:41:03 siduction64kdefx sudo[31180]: goineasy9 : command not allowed ; TTY=pts/2 ; PWD=/home/goineasy9 ; USER=root ; COMMAND=/usr/sbin/hddtemp -nq -u C /dev/sda
Feb 17 14:41:03 siduction64kdefx sudo[31197]: goineasy9 : command not allowed ; TTY=pts/2 ; PWD=/home/goineasy9 ; USER=root ; COMMAND=/usr/sbin/hddtemp -nq -u C /dev/sdb
Mar 28 19:17:27 siduction64kdefx sudo[31522]: goineasy9 : command not allowed ; TTY=pts/2 ; PWD=/home/goineasy9 ; USER=root ; COMMAND=/usr/sbin/hddtemp -nq -u C /dev/sda
Mar 28 19:17:27 siduction64kdefx sudo[31539]: goineasy9 : command not allowed ; TTY=pts/2 ; PWD=/home/goineasy9 ; USER=root ; COMMAND=/usr/sbin/hddtemp -nq -u C /dev/sdb
Mar 28 19:17:59 siduction64kdefx sudo[1156]: goineasy9 : command not allowed ; TTY=pts/2 ; PWD=/home/goineasy9 ; USER=root ; COMMAND=/usr/sbin/hddtemp -nq -u C /dev/sda
Mar 28 19:17:59 siduction64kdefx sudo[1174]: goineasy9 : command not allowed ; TTY=pts/2 ; PWD=/home/goineasy9 ; USER=root ; COMMAND=/usr/sbin/hddtemp -nq -u C /dev/sdb
It came up twice since the beginning of the year. Something intermittent?
Edit: Interesting, but I'm not sure if related, on my gkrellm, I can't get a reading for HD temp on siduction, but it does come up on my openSUSE installs.