I never saw this before my flight last Saturday from LAX-SLC. I was sitting in F and the FA told a guy sitting near me "to please don't put your laptop in the seatback pocket" and she said it quite the attitude. The guy seemed like he didn't know what she was talking about and said "excuse me?" and she said, again with a huff, "please don't put your laptop in the pocket. it's breaks the seat."