I wonder about the translation of this passage from Tom Sawyer:

Earnest, Huck -- just as earnest as ever I was in my life. Will you go in there with me and help get it out?

— En serio, Huck. En mi vida hablé más en serio. ¿Quieres venir a la cueva y ayudarme a sacarlo?

It seems to me that maybe "En mi vida no hablé más en serio" instead. Or perhaps "No hablé en mi vida más en serio" or something similar.

Am I wrong? It seems to be saying, "I have spoken more seriously in my life" when it should be more like, "I have never spoken more seriously in my life."