I experienced an extremely hard brake pedal once not to long ago but it was not from what is described in the recall.
I was coming home from Import Alliance in Kentucky (roughly 500 mile trip each way) and had been driving for a few hours with out really using the brakes. Come into traffic and hit the brakes to slow down and it felt really hard to press. Brakes worked fine but was a bit scary at first. Just happened that one time on the trip home. But for the next few days after returning home, when first starting up in the morning and for a few minutes after, the brake pedal was super stiff, and I mean really stiff/hard with out much travel at all. It seemed to work itself out after about a week or so. Related? Possibly.
I have not had any issues with it since.
I go in next week for the recall repair.