If I recall the fbi stated after the Pulse nightclub attack, they aren't allowed to monitor an individuals social media past 6 months, unless there is enough to get an extension. Yes, here it is-
Murphy, the FBI’s former number two who worked with then-FBI general counsel Valerie Caproni in revising the bureau’s investigative guidelines, says they discourage agents from monitoring potential terrorists over the long-term. Those guidelines retained the requirement that any preliminary investigation that did not produce evidence of a crime must be closed after six months. “Someone should have been monitoring [Mateen’s] social media 24/7,” Murphy says. “but under the guidelines that is not allowed,” he says.
from Time.com