^Even with taking a shower you mean? And they just stuck in there, also possible. Could have been a quick shower with no hair washing.
Also thinking about it, Silence only noticing the feathers after Saria dashes off to work is a pretty funny thought. Maybe she realized the embarrassing situation Saria is experiencing. Which could lead to Silence having sex with Saria again that night, partly in hopes of making Saria feel better. However it only starts the cycle over the very next day haha