Unrep Sub: Say Something or Stay Mum?

[Dakota]

Rule 4-6-C-5 says

5. When a runner and that runner is brought to the attention of the umpire BEFORE a pitch, legal or illegal, or a play made;
EFFECT: No penalty. Replace the unreported substitute with the correct
player or enter them as a legal substitute.

(Yeah, I know, your situation is a batter...)

The rule does not state any conditions about who brings it to the umpire's attention, or how it is brought to the umpire's attention, only that it is brought to his attention. In your situation, the player herself brought it to your attention by being physically distinctive.

Personally, I wouldn't have intervened, but you do have that principle to hang your hat on.