Zoro doesn't know too much about his own parents. He could go on and on about his sensei and the man's daughter, Kuina, but not his own parents. He does, however, listen as Alex mentions that he'd been running toward something when he got to Madison Valley. Where as the former pirate hunter had been out in the open sea, on a ship... with his crew. "Maybe it's different for everyone."
He hadn't been angry at anyone. Hadn't been running toward anything. No, he'd been on the sea and they'd been heading toward the Grand Line. A part of him still wonders if that was a part of it all.
"Since you know where we're going, I'm following you."