is one piece episode 762 filler?

As Wanda, Carrot, and the Straw Hat Pirates go off to see Nekomamushi, Wanda remarks on the full moon in the sky, saying she is glad it is covered by clouds. Luffy then says that Sanji and Caesar Clown were still present on Zou in her story, asking her what happened to them later.

Wanda hesitates, and Brook decides to explain it himself. He tells the Straw Hats that most of the minks were not told about this, and this may be hard for them to hear.

He then reveals that Sanji is likely not coming back, which angers Luffy, who pointed to the note Sanji left, which states that he would be back.