She wore it while boarding the plane in Maryland, not while visiting the children in Texas. If it was directed to anyone (which officially it wasn't), it most certainly wasn't the children.
Everyone’s concerned about optics.
Optics:
2 chiefly North American (typically in a political context) the way in which an event or course of action is perceived by the public
The props on a stage, political theater where issues are made secondary to the event.
In other words, the visual manifestation of political correctness.
If nothing else, this first family breaks from business as usual, optics be damned.