After I left my last place of employment, I sent my boss a long email with explanations where to find everything I worked on and how to make sure everything works (including every module I used).
The first reply email was a dry thank-you. The second one was very worried and upset.
Turns out he went and opened each module he saw in the email and when he noticed the licencing on them, he was extremely shocked that I took the liberty of open-sourcing everything, like File::Find and LWP::UserAgent.