Actually when I wrote that example, I heard the speaker pause to slide the paper across the desk. If t was intended to sound melodramatic or aggressive.
The question, to me, isn't whether or not the speaker paused. It's whether or not the speaker was interrupted. For a pause, all you need is a tag or a beat. And I still don't see how a speaker would interrupt himself. The closest thing I can think of would be if he does something accidentally, like dropping something: "You know, I don't have any--" he began. The glass slipped from his hand and shattered on the floor. "Well," he said, "guess I gotta clean that up now." The interruption uses a dash inside the quotes. The pause uses a tag. If I didn't want the "he began" bit (as it does slow the text down), I'd go with separate lines: "You know, I don't have any--" The glass slipped from his hand and shattered on the floor. "Well," he said, "guess I gotta clean that up now." Actually, I like the second one a lot better.
Fair enough, but as @xanadu alludes to, there's better and more conventional ways to get this 'pause' across. Your example with the dashes wouldn't indicate a pause if I were to read it, it would just stand out as strange/incorrect syntax/punctuation.
I can see what you're doing here and it can be tricky. I understand you don't want to use the action 'traces a line down his nose' either before or after the line of dialogue, because you want to make it clear he's doing the action while he says the line, but to me it doesn't work because it forces the reader to break what should be a continuous line of dialogue. I've encountered the very same problem myself a few times, but in the end I just go with the action either before or after the dialogue (can't remember which). In your example I'd have gone with before, so that the gesture is still in the reader's mind when they read the dialogue.
