Popup without ANY indication what was installed or why.
No mention of anything in AppStore Update history either.
They do that already for regular security updates.
Why not for the auto-pushed one ?
At least I would have expected to see a "Security update automatically installed on December 23. Click here for more info." message.
I agree. You can find the install info, but not in the App Store where you'd expect to see it.
About this Mac -> More Info (opens System Info) - under Software, click on Installations, then click on the Install Date header to sort.