Pietro didn't address it either. He didn't want to explain that he'd been seeing his mother- a woman's who's face he never remembered seeing in the flesh. He knew he wasn't right, but admitting that out loud... If his father knew just how bad his mental state was he'd never trust him.
"I'll get her. Thank you, father," he said, bowing his head and turning to take his leave and fetch Mystique for him.