Accidently gave essay notes to a classmate
You have taken appropriate action already. If you meet up with the person warn them against using the notes. But, if you want some additional security, print out your notes and get someone you trust to sign and date them. Now you have a clear marker. I doubt that this is necessary, but if you are paranoid,...

But any infraction of rules would be by the other student, not yourself. Notes are just notes. Relax.