I didn't see the dress in full- most photos cropped it at her waist.
But I do think that white lace was not quite formal enough for the occasion. it looked a bit 'little girlish' almost wedding-y.
Bearing in mind she'd whip it off on the plane and put on joggers and a T.
I agree that choosing to accompany your H on a business trip is dated.
She's made such a thing (or he has) about continuing with her NHS role so pity her poor patients needing OH assessments when she's in the US.