No, Waiting in line - is the normal collocation, at least in this part of US. In Elvis Presley's classic hit " Are you lonesome tonight" , there is a line Other ... Then they can bring the curtain down. Is your heart filled with pain ...
In the old days, curtains are raised and lowered (down) in theaters when a show was over. But cur
The curtains are down. Let me clarify. It's correct grammar, but that fact does not tell you anything about whether the expression is odd or natural or sense or nonsense.
I've never heard anyone say that in a normal situation, ie where curtains can move sideways.
I wonder if the OP simply misheard "drawn" as "down."
New Yorkers (as far as I know, no one else) wait "on" line. Since I grew up there, I thought it was the normal way to say it for a long time. It's just a regional variation.
If referring to a theater or other stage production it would be common to say, "The curtains are down." If speaking of one's home this would be unusual. "The curtains are closed" would be the typical expression in that case.