Understanding what MIAB is telling me

I’m now getting these messages, but not sure what changed. I was starting to get another message because my secret key changed. I’ve fixed that, so that message hasn’t returned, but this one’s still with me. Is something broken, or is there a way to turn this off?

Subject: test -x /usr/sbin/anacron || ( cd / && run-parts --report /etc/cron.daily )

/etc/cron.daily/apt:
verbose level 1
power status (255) undetermined, continuing
system is on main power.
sleeping for 1618 seconds
power status (255) undetermined, continuing
system is on main power.
check_stamp: interval=86400, now=1505890800, stamp=1505804400, delta=86400 (sec)
apt-key net-update (failure)
download updated metadata (success).
send dbus signal (success)
check_stamp: interval=0
download upgradable (not run)
check_stamp: interval=86400, now=1505890800, stamp=1505804400, delta=86400 (sec)
unattended-upgrade (success)
check_stamp: interval=0
autoclean (not run)
aged: ctime <7 and mtime <7 and ctime>2 and mtime>2