For one brief second after she looks at him with Full Offense, Cassian's expression essentially boils down to the epitome of Oh shit. Did he use the wrong English word? No, no, he's pretty sure ma'am was correct. Maybe he stepped in too close?

Immediately he takes two steps away, giving her space and folding his arms behind his back. "My apologies."

What is he apologizing for? Who knows! Whatever he offended her with! He avoids the use of ma'am, just in case, taking in the sight of her with her unhappy baby. Her hair is wispy in the wind but tied up neatly, and her dress is fine enough material that he just assumes she is a first class young mother, given she is on the first class deck too.

"If you and your daughter need anything, I will be happy to help, otherwise I will let you carry on."