I think before Enma, Zoro's Haki was just lying dormant inside him, that's why nobody noticed it, after Enma, Enma brought it out by drawing on it and making it go out of control, and now he can "leak" it all the time. In Ashura vs Kaido he used it unconsciously, it wouldn't make sense for him not to use it and for Kaido to comment on it.
I think there's an explanation about dormant Haki, that a person can simply spend their whole life with it dormant and never awaken it.
I think there's an explanation about dormant Haki, that a person can simply spend their whole life with it dormant and never awaken it.


