Comma question

[kazewolf]

In this extract.
"Hello, Mrs. Spade. I'm Pierre Tardivel." He was conscious of how out-of-place his Québécois accent must have sounded here -- another reminder that he was intruding. There was a moment while Mrs. Spade looked Pierre up and down during which Pierre thought he saw a flicker of recognition on her face.

Wouldn't it be better if there were a comma between "down" and "during", like the below modified version, or is it just unneeded and incorrect.

"Hello, Mrs. Spade. I'm Pierre Tardivel." He was conscious of how out-of-place his Québécois accent must have sounded here -- another reminder that he was intruding. There was a moment while Mrs. Spade looked Pierre up and down, during which Pierre thought he saw a flicker of recognition on her face.

Thanks.

[Rover_KE]

In my opinion it's unnecessary but not wrong, in view of the fairly long clause ending with down.

Rover

[kazewolf]

Thanks Rover,
so the clause "during which Pierre thought he saw a flicker of recognition on her face" is a dependent clause(but a dependent clause starts or ends with a subordinating conjunction but in this case it starts with a preposition.)?
Or is it a modifier? But what is it describing(is it describing the time when Mrs. Spades looking up and down.)?

Thanks.

[bhaisahab]

"There was a moment, while Mrs. Spade looked him up and down, when Pierre thought he saw a flicker of recognition on her face."
I would write it as above.

[kazewolf]

Sorry, never mind about my above post; I got mixed up a bit. I came to conclusion that it acts as a modifier/dependent clause.

Thanks bhaisahab, however the phrase "when Pierre thought he saw a flicker of recognition on her face" is a bit confusing(because of the misplaced modifier?)

Sorry, this is really getting out of topic.

[Raymott]

"There was a moment, while Mrs. Spade looked him up and down, when Pierre thought he saw a flicker of recognition on her face."
I would write it as above.

Yes, or "moment ... in which".
The author is confusing the longer time period of Mrs. Spade's looking with the moment of Pierre's thinking/seeing. "During" is wrong for the latter.
I hope this isn't a well-known author.