That hint leads him to figure out exactly what's nagging at his memory, thanks man. It takes a moment, but then Cao Pi gets that universal look of "aha" dawning on his face. "Yes, we have," he acknowledges. "It's been a year since we witnessed each others' deaths." And that's when his eyes come up, with a pointed look. "I believe at the time I said something about the date being terribly unlucky. I had no idea it could get even worse a year later."