Does Apple push updates that require a restart within a set timeframe? Just got this notification on my MacBook Pro running OS 10.12.6. 



It reads:


  macOS updates have been installed.  This computer will restart in 60 minutes. Please save anything you are working on and log out by choosing Log Out from the bottom of the Apple menu.


Four things about it strike me as un-Apple-like:


The tone
The unfamiliar, unnecessary icon
Forcing me to restart instead of providing a choice
Non-conformity with Notification Center notifications pushed by the App Store


This raises three questions:


Does Apple push updates that require a restart within a set
timeframe?


If so, since when, and why?
If not, should I be suspicious of this notification?
No, this is not Apple. If macOS has not been able to install updates without interruption, Apple software updates will show in Notification Center and will not force you to update.

The message in your question is from an MDM provider your organisation has installed on your computer, which in this case is JAMF. You should contact your organisation if you have any queries about the actions taken on the computer.