Facebook Security Check message

Hey Guys - on one of our LP's we are randomly getting a security check message appear when people share the page.

Our host domain is secure and we've been through all of the images, links and OG Tags and everything is in order. The problem doesn't seem to be occurring with every share, it is random and only occurring with certain users. Quite likely another annoying FB oddity but just thought I'd ask if this issue pop up for anyone else?