"I'm afraid all we can do is sing as we go," Q tells him rather apologetically.
"Of course," he agrees. "Mmmm..." Q's face screws deeper into it's thinking frown. "Fairly strong, I think. The brighter the colour, the stronger the energy. And it will make the potion less noticeable in the juice." He consults his notes one last time.
"That's what I've been able to gather as well. However, I've found no outward evidence of anything that might have caused such an anomaly at that time."
"Well yes, and because it was you asking, he told you. It would be very unusual, not to mention suspicious were I to ask the same question," Q explains earnestly. "What did he tell you?" he asks, almost as an afterthought.