Lucy's being pleased at her own orneriness is interesting. Being happy that she's difficult to be around is a very Lucy attitude. This might be overthinking a joke somewhat, but it does point the way to her increasing willfulness.
In this strip, Lucy is alone but she's still talking. Her speech is more like her thoughts than things she is actually saying. This is akin to the theater trope where characters turn and address the audience, unheard by others in the scene. Overturning this, later on there will be strips in which a character actually overhears another character's internal dialogue, which could be taken to mean that either Schulz is playing around with the convention, or that his characters really do frequently talk to themselves.
The text of ROASTED PEANUTS is copyright 2009-2011 by John Harris. No copyright is claimed over the comic strips, which are here under the principle of fair use. Strips presented for review purposes only. We love Peanuts a whole lot, and wouldn't dream of exploiting it. Please don't sue us; we're only trying to love. Thank you for reading this notice.