Even if Redcloak was trying to hide lost time, I'm having a real hard time seeing how Niu's survival would lead to it being revealed. "Foul lich! Your goblin slaughtered the resistance at exactly 4:52 on Thursday!"
"Wait, 4:52? Why didn't you bring the phylactery to me until 6:30, Redcloak? And yes, I memorized the exact time you brought it to me!"