Darcy - I think the answer is based on two questions you should ask yourself.

1. Do you want this client as a repeat?
2. Did taking the time to learn this new information hinder or advance your career? In this case, I'd say knowing that information and having it available for your clients in the future is going to 'advance' your career. So charging the client because you had to find this out seems irrelevant. You are designing the website for her in the first place, so technically she is already paying you for your services. You are just legalizing it under Canadian law, so have the client foot the bill + an extra small percentage if you wish.

Just my two cents,