I just got a popup that said something like there is an update available, but we need your help... with options to snooze, restart now, or something else.
After I clicked on Restart now, nothing seemed to happen.
Windows update popups are annoyingly legit. Whether that one was legit is anybodies guess. I would say it was but run your antivirus and your antimalware and if nothing is picked up go on with your life.
Also in that area, is a list of completed updates. that way you can be sure it actually installed it.
I had an issue about 6 months ago where one update kept failing to update automatically, so i had to force the update. (granted i'm on the slow lane for insider preview)