iPhone alert regarding password security

I was attempting to sign into an app (it has a stored password and user name, so it should have happened automatically) when what I think was an alert from Apple popped up saying that stored passwords on a number of sites I use had been compromised through data leaks and should be changed. I Googled information about that, and it seems to be a legitimate message. I followed the directions in an article from a Mac-related publication about checking password security in settings to see which might have been compromised and found some that I think should be updated ASAP. But before I go down that road, is this actually a message from Apple?