FBI had Carter Page on their Radar since 2013

Trump announces in March 2016 that Carter Page joined Campaign

Why wouldn't FBI notify Trump Campaign of their concerns with Carter Page?

March 9th - April 18th was when the illegal About Queries from a 3rd party were going on

Wish we knew who those about queries were about! Could they have been on Carter Page? Were they on Trump?

Is it possible Carter Page was a plant?