Did Apple really auto-install the NTP Security Update?

I resist headlines that end in question marks, but I think it's appropriate this time. When Apple issued its NTP Security Update earlier this week, Reuters reported that it was the first time Apple pushed an automated security update to Mac users. This seemed to be confirmed by Reuters in a conversation with Apple spokesman Bill Evans:

The company decided to deliver the NTP bug fixes with its technology for automatically pushing out security updates, which Apple introduced two years ago but had never previously used, because it wanted to protect customers as quickly as possible due to the severity of the vulnerabilities, Evans said.

But in my post regarding the Reuters article, I noted that the update wasn't automatic for me. I installed it the typical way, by clicking a button in the updates section of the App Store. And users in many forums posted mixed experiences, with the update being automatic for some and not for others. 

(I should add here that some were upset over the idea of Apple automatically installing updates  - even critical security updates. Hence the follow-up articles like below.)

Gene Steinberg posted one possible explanation for why some Macs were automatically updated and others not. In the App Store pane of System Preferences, there's a checkbox for 'install system data files and security updates'. He suggests that only Macs with that option checked had the NTP Security Update automatically installed. But than there's Shawn King. In his post on The Loop, in the comments section he states that he had automatic updates disabled on his Mac - yet his Mac was automatically updated.

System Preferences App Store PaneSo did Apple really auto-install the NTP Security Update? Borrowing from the Mythbusters, I'm labeling this one 'plausible'. As for the controversy surrounding Apple pushing automated security updates, I'm labeling that as 'much ado about nothing'.

Update: This Apple support article states that "your Mac installs OS X and app updates overnight." So maybe it's as simple as some users installed the update before it was automatically installed by the system.

[h/t Srikar Dhanakoti for leading me to Gene's post]