For other poor souls that may have run into this, I was able to solve this "mistery"...
I called the 800 number, explained what was going on and was told that yesterday another Pie update had been released. So, I backed up to my computer as much as I could of the files on the S9 internal memory and proceeded to run this other update.
Lo and behold, after it finished (and it took MUCH less than the update last week), the phone now has a new Baseband, Build Number and Android Security Patch Level.
Baseband and Build Number now ends in "AG", before it was "AB".
Android Security Patch Level now has February 1, 2019 as the date. Before it was January 1, 2019.
THIS IS NOT THE DESCRIPTION OF THE UPDATE THAT YOU SEE WHEN YOU TAP ON "LEARN MORE" IN THE SCREEN WHERE YOU ARE GIVEN THE OPTION TO "INSTALL NOW" OR "INSTALL LATER".
The description is instead identical to the one in last week's update, down to the baseband code and the date of the Security Patch Level. This is totally misleading, as last week update was indeed the major update from 8 to 9. Today's update seems to be just a patch or minor tweak.
To make things worse and even more confusing, going to the Verizon's website page listing the (supposedely) last update, there is no mention yet of todays "AG" and Feb 1 security update. It still shows the original update from last week.
Bottom line: this is indeed a follow-up to the previous, major version update to Pie. I got concerned because with no changes in the description and version of the update, it looked like it was trying to install Pie again from scratch. This has never happened to me before (I have been using Android since version 1.6), so I was worried that trying to re-install the same update would brick the phone.
Luckily, happy ending.