Well, first of all, you should definitely not have signed and returned the seizure notice. Believe me, nothing good could ever come to anybody for doing that. But that doesn't mean you should worry. I wouldn't. I've been extremely lucky, and only had one seizure in five years. A relative of mine signed and returned a 'love letter' and never heard a thing after that.

About when the seizure was from, it's hard to say. Three months after I got my notice, I received another thing listing several different meds with my order, none of which was ordered by me Customs really isn't the most organized place