We never get a glimpse of Nephi’s sense of humor. It is doubtful that when he wrote this, he was aware of the humor of the situation. Nevertheless, the juxtaposition of the reactions of Nephi’s brothers and Laban’s servant would make a humorous break in the tension of the situation.
Nephi’s brothers had personal experience with a Laban who threatened to kill them. They surely worried that Nephi might have been killed in yet another failed attempt. When Nephi returns, Laman does not see Nephi, but just as Laban’s servant did, he sees Laban. His worst fears are fulfilled and the brothers prepare to flee before him.
Nephi calls out to them, and with whatever he said, was able to convince them that it was indeed he, Nephi, and not Laban.
Whereupon, it was the servants turn to panic and attempt to flee. Nephi solved the first crisis by creating a similar one, but with the servant running toward Jerusalem rather than the wilderness.
It was a rapid turn of events. If it were part of a film, it could easily provide a brief comic break—even though the situation was deathly serious. Literally.