Resetting Password

A couple of weeks ago I got an email from Comcast/Xfinity saying I needed to reset my password for security reasons.  I did so and everything works fine.  (I can't seem to find that email anywhere on my system)  Then today I get a letter from Comcast/Xfinity saying that my password was reset and wanted to make sure that it was me that did it.    Is this all legit?