Just having a thought that Gus killed Lalo but didn't like...defeat him.
Lalo gave Hector that bell from that shootout they had at the hotel and despite the fact that Gus did his whole speech about that animal he kept alive as his prisoner just like he was doing to Hector it didn't stop the fact that that bell that Lalo gave Hector was the trigger for the bomb that killed him.
Gus killed Lalo but for the rest of his interactions with Hector, ostensibly the Salamancas, he was haunted by the literal echo of Lalo the entire time.