Mysterious emails never mean anything good.
A thread on NeoGAF has sprung up suddenly, noting that there's a huge amount of Origin users flocking to the official forums to ask about either their confirmed changed password (which they did not request) or the fact that they couldn't get into their account.
The post also points out - rightfully - that the email sent involves no mention of what the username/email was changed from, there's no confirmation email involved, and since all the information is able to be changed, security questions and answers or date of birth cannot help verify authenticity.
IGN received the following statement from EA, who deny any failure in security, after many requests for clarification from numerous journalists:
“Anytime a player has a question about the security of his or her account or personal data, we take it very seriously and take all possible steps to help. For any customer who cannot access their Origin account for any reason, we ask them to please contact Origin Help or EA’s customer experience group at help.ea.com. The robust security measures in place to protect Origin users accounts are constantly being expanded and upgraded, and we also strongly recommend customers take the protective steps of using strong passwords and changing passwords often.”
Julian "Mirai" Williams