The Cannondale bikes this is happening on already have a CF fork.
I can believe that C'dale replaced a bike due to this particular kind of brake shudder. If this customer's bike is like mine, and it sounds like it, it's basically unsafe in traffic because there's no way you can do an real emergency stop - the front wheel shudders and hops around so badly under hard braking that it loses contact with the road and wipes out. Which would be a concern I imagine for a company in todays world of lawsuits.