Themes
Isn’t it peculiar, Charlie Brown, how some traditions just slowly fade away?
— Lucy van Pelt · A Charlie Brown Thanksgiving

Behind the line May contain spoilers.
Our reading
An editorial interpretation.
The question draws attention to traditions disappearing gradually, rather than ending in one decisive moment. Addressing Charlie Brown makes the observation conversational, while 'peculiar' gives it a note of puzzlement. Something assumed to endure is described as quietly slipping away.
Context reviewed