He’s pretty playful in “Attack of the Clones” when Kenobi is looking for Kamino. “Master Kenobi has lost a planet, how embarrassing” or something along those lines.

He’s also teaching Younglings in this scene, so being more playful is fitting.

Most of the time we see Yoda he is at the council or doing war things, so you can’t really be a silly goblin in those cases.