Molly Moon/Headscratchers

Just Bugs Me:

In the first book, Lucy Logan takes off Molly's hypnosis using the phrase "perfectly punctual."

And looking out the window at the full moon, she added, "And perfectly punctual."

However, in the second book and other sequels, when interrogating Cell, he reveals the password as "perfectly punctually."

Those words. Those two unusually joined words had been used on her. Used to wake Molly the first time she had ever been hypnotized. Used by a person who Molly trusted. And those very same words were the ones Primo Cell used to control his victims.

But they are not the same words, and yet the characters go on saying that they're the same. The obvious reasoning for it would be this sentence in the first book:

"What did you mean when you said come back 'perfectly punctual'? I can't remember making any arrangement with you."

But that doesn't make any sense either, because Molly is ten and can be expected to not know how to use adverbs yet. The way Lucy used it originally made sense grammatically. But to change the entire series password because the above sentence makes more sense with an -ly, even though the original usage was correct? What?!