I didn't have to agree with anything to see if I was possibly affected. You do, however, have to agree to that stipulation if you sign up for their free credit monitoring service for one year.
I found out I was affected (hubby wasn't). I am beyond pissed. One year of free credit monitoring when my info is now out there for the rest of my life? I don't trust them to monitor anything when they couldn't be trusted to keep it safe in the first place. Besides, I don't expect them to survive this. I signed up both hubby and me for Identity Guard.