Galaxy S4 Update is ready to install. Is this a virus?

[AC Question]

I got a popup message on my Galaxy S4 Lollipop 5.0.1. "Update has been downloaded and is ready to install. Click the button at the bottom of this message. Update size 468.56 Mb...." Quite a long message. It didn't say who it was from or what it was updating so I backed out of it. However it popped up twice a day for a few days, but today I hit the back button again and it installed anyway, restarted my phone and updated the operating system. The only difference I can see is the lockscreen grid is slightly smaller.
I believe Samsung stopped supporting Lollipop in 2015. Is this a virus? How do I find out?

 

[smvim]

I believe Samsung stopped supporting Lollipop in 2015.

Not to nit-pick on details but Samsung has nothing to do with supporting Lollipop, Android is owned, maintained, and developed by Google. The problem basically is Google does keep pumping out updates and patches, it's just that the carriers and phone manufacturers -- the ones who took on the responsibility of pushing out those updates to their customers -- have done a pretty bad job at it.
Anyway, Lollipop (version 5.x) is still supported. Is your S4 still showing v. 5.0.1 or has that changed? Who is your carrier?
https://en.wikipedia.org/wiki/Android_version_history