Creepy Facebook pop-ups rolled out when friends are "becoming extremists"

Facebook has started monitoring posts and sending people pop-up boxes whenever it thinks you might have been exposed to an "extremist" friend.
Facebook responded to questions about the alerts Thursday, issuing a statement that says:

“This test is part of our larger work to assess ways to provide resources and support to people on Facebook who may have engaged with or were exposed to extremist content, or may know someone who is at risk,”