Was Yahoo Mail Hacked?

When I went to login to my Yahoo Mail account, I was forced to change my password "due to unusual activity" on my account. I'm currently visiting family in a different state, so I figured it had something to do with the location I was signing in from. I mentioned it to my family and my uncle said that he too was forced to change his Yahoo account passwords. Anyone have any information on a system wide password change requirement or was Yahoo hacked?