What is Goku referring to here?

[Hector]

In 3.32, when he says Piccolo's ki surged, is he referring to Piccolo being stronger due to merging with Nail or to a silent power-up?

 

[GSM123]

Given the context with all the flashbacks it looks like he’s talking about fusion.

This is weird though. I remember Goku couldn’t even recognize Piccolo’s Ki in the manga.

 

[Papasmurf]

That section has a bunch of plotholes. Ex: Dende overhearing about Piccolo's fusion with Nail which he wouldn't find out until after Namek explodes

 

[Hector]

Given the context with all the flashbacks it looks like he’s talking about fusion.

This is weird though. I remember Goku couldn’t even recognize Piccolo’s Ki in the manga.

Are you sure it's not an additional filler powerup? Right before Goku saying that, Piccolo had started dodging Freeza easily, which indicates a silent powerup?