This is ugly.
Facebook was collecting messages from people who never consented to Facebook’s privacy policy. Update: FB says they were not “storing” the text messages, only the meta data of who sent/receive messages. That does not mean they were not scanning your text messages, only that they have said they were not storing them.
Facebook adopted the NSA’s internal motto: “Collect it all“. Indeed, Facebook is likely in a close working relationship with the NSA as another profit opportunity.