This is reasonable time to wash your chicken and also likely where this habit comes from. Before the age of factory farming and the advent of reliable home refrigeration a lot of meat was improperly stored before and after selling.

Washing your produce was likely a good defense mechanism to wash away actual dirt, grime and bugs that may have adhered to it. Nowadays it's largely unnecessary unless you're still living in a place where butchering and processing techniques may not be of the greatest quality.