As we saw in the last chapter, Luffy has been completely defeated (off-panel) by Kaido and sent plummeting from Onigashima to presumably the sea below.
At the end of Chapter 1013 Kaido says: “It’s been a while since I got this fired up”.
Now, it is highly unlikely that Kaido is referring to him going Hybrid, because even after that, Luffy was still able to trade blow-for-blow while in base form, even clashing with him equally.
If Luffy was able to clash equally with Hybrid Kaido while in BASE form, that means Luffy would have simply steamrolled Kaido the moment he entered Gear 4, assuming he could use Advanced Conqueror’s Haki in Gear 4.
Obviously, the only way for Hybrid Kaido to handle Advanced Conqueror’s Haki Gear 4 Luffy is, assuming he didn’t cheat like he did against Oden, is by revealing his Awakened form.
Awakened form is probably what Kaido meant when he said “fired up”. If it wasn’t Hybrid form, than I don’t really know why Oda would bother off screening this and having Kaido word it this way.