is attack on titan (shingeki no kyojin) episode 38 filler?

At an unknown time, Eren Jaeger looks out over the sea as gulls fly overhead. His hair has grown long and shaggy, and he reflects on how, though Armin Arlelt always told him there was a sea beyond the Walls, he has always wondered what was beyond it.

In the present day, Eren and the remaining members of the 104th Cadet Corps settle into a remote rural cabin. They bicker over cleaning, Sasha Braus stealing food, and Mikasa Ackermann working out so soon after having been grabbed by a Titan.

It reminds them of their time together in the Cadet Corps, but times have changed.