Neva only played a part in it.

So when talking about Super Saiyan 4, Goku said that he's been training hard ever since the fight against Buu and said that he wasn't sure it would work when Vegeta said he hid it from him. Seems like Goku already know that there's a level beyond Super Saiyan 3 and was working towards it, but Neva healed and gave Goku just the push that he needs.