Is it a major DL no-no or a breach of breezeway etiquette to self scan?

At one gate in ATL, with 2 scanners and one agent, I breezewayed up to the unused scanner, ran the BP under the head, and got the "warble" for exit row. GA looked up, said something in heavily accented English, that I missed, but didn't move an inch to stop me when I kept on going to board the plane.

Just another example of how a good concept is lacking somewhat in implementation, I suppose.