I don't know about this particular update, but when I used to work for an AV vendor we did like 4 "data" updates a day. It is/was about being quick a lot of the time, you can't stage those over 3 days. Program updates are different, drivers of this level were very different (Microsoft had to sign those, among many things).

Not thay it exuces anything, just that this probably wasn't treated as an update at all.