If you get a Netflix password reset email, don’t panic, as it is most likely legitimate! Recently there have been huge public postings of usernames and passwords from hacked sites such as LinkedIn and Tumblr. Netflix takes the proactive approach of analyzing the decrypted passwords found within them. They then compare those passwords and associated emails with those of their subscribers. If there is a match, they automatically reset the subscriber’s password. Once a password is reset, they send a notification to the subscriber explainingn why this action has taken place.
Source: https://www.bleepingcomputer.com/news/security/netflix-automatically-resets-passwords-for-pwned-subscribers/