The series, which stars Australian actor Dustin Clare as new gladiator Gannicus, is currently airing on Starz.
Hannah told TV Squad he had been concerned that the six-part series would not match the quality of Spartacus: Blood and Sand.
"There was a little sense of anxiety about that, because I'd always felt that every episode of the first series was fresh and original and exciting," he explained. "It obviously hadn't been the plan to go back and do this, although there [had been some ideas about doing some] flashback stuff."
However, the actor, who plays scheming slave master Batiatus, claimed that the prequel has "a very organic story... to tell".
"I was kind of a little [anxious] waiting to see it, but then I started reading it," he said. "It was so exciting and it didn't have any sense of cynicism about it."
Spartacus: Gods of the Arena continues on Fridays at 10pm on Starz.