I'm sure that was the case.
What is not right is this:
If I were to have left this at 10 years, or any other term (or if the client changed this from their account), there would have been an invoice for $0, the service would have been renewed and in the case of a domain, we can't get our money back from the reseller or undo that renewal within a resellers system (I could see this being the same for GoGetSSL, TheSSLStore, Enom, etc). That leaves us on the hook and hoping the client is faithful and pays for the 'upgrade'.
Also, there is no email sent to any of the company admins stating that a change was made. I think this would be a nice feature to have and I can make a feature request for it.