Change of password when i did not change it.

I recieved an e-mail this morning saying my password change was successful. I did not change my password.

The E-mail did not ask for any information nor did it provide a link. So i logged onto my Apple ID account, and changed all passwords, and security questions then added the two step security option.

My question is should i report this to Apple and if so how. The only option is phone call, but i'd rather just report it via message/e-mail and let Apple deal with it. Also which forum is more appropriate. I cannot find a forum so chose this one to post the question.

Thanks.