You're right - it was "premium economy" from rows 7-14(approx) in a brand new 777. Premium economy was the flat shell sleeper seats that were in business class when I flew JL last summer! What a treat!

(This also highlights how, despite being an AA frequent flier, I think JL is my favorite airline. We flew "business" on AA 777 from JFK-NRT and the plane had the old lounge-style seats, and the overhead lights and personal video were broken.)