I love this strip. The joke is actually kind of subtle, that Lucy's fussiness (slowly being established through showing, instead of just telling) might actually have a rational basis, and that Charlie Brown could be convinced of it. (Or, alternatively, Charlie Brown has a very dry sense of humor.)
I can't imagine any other comic strip choosing to make this kind of joke in exactly this way. Maybe Bloom County, but no it'd have made it a little sillier. Maybe Mutts (with Mooch in Lucy's role?), but no, Earl wouldn't take Charlie Brown's line at the end. This style of humor, in comics, is unique to Peanuts.
I can imagine Lucy's making this explanation on Ask Metafilter or something. (Her username would be "fussbudget," of course.)
