Originally Posted by MSPeconomist

Absolutely report it.

A couple years ago I had a nasty situation with nonrevs taking my seat (that I had already occupied, when I went to use the lavatory at the gate) and then not wanting to move (the guy even kindly spilled his PDB beer on my pillow), and finally doing a passive aggressive routine of pointedly disturbing me during the flight as if to make me sorry that I had insisted on getting my seat back. At the time, I didn't report this beyond trying to get the FA involved in making the jerk move back to his assigned seat (it was mommy, daddy, and older teen daughter), but in retrospect I wish I had made a big fuss so that the airline would revoke the jerk's nonrev privileges for his behavior.