Duty first- that much hasn't changed. Arguably it will never change, not anytime soon at least.

"I spent enough time doing the bare minimum that I can do no less than give my everything to my work, Sister." He pauses, then, making a bit of a face. "It...may be in part because of this that I did not come to see you sooner."

That's likely the closest he'll probably come to admitting he's overworked himself.