Swamped

You opt for simple lecturing. That might convince him you're buying it. But you try to sound a little skeptical - don't want to seem like a pushover or he'll suspect you're playing along.

"That stuff's for medicine, you know. The doctor might need it, and besides, I'm pretty sure making it taste good isn't a priority. And if you'd just asked twenty minutes ago, I could have grabbed you something from the bar."

"Yes, obviously I haven't been thinking clearly." He seems to be committing to the bluff, at least. "I think it's this lockdown pushing me over the edge, though. No way I could get a drink through that..."

You think this is a play for sympathy.

"Well. Why don't you get back to your bed, and I'll see what I can do about finding you something. Just come on out."

You open the door, but you also step to the side a bit. Maybe he won't recognize you in however many years, but you don't see a reason to make it any easier for him to do it.

There's no response. You don't like this. Maybe you sounded a little too gullible and he pulled a vanishing act.

On the other hand, he also might be cautious because he can't see you, and he's waiting for you to make a move. But then, couldn't he ask where you are if that was it?

If you weren't dealing with a wizard, you'd probably just take your chances peeking in there. But that seems a lot riskier when magic's involved. You'll need to think carefully about what to do next.