Not being educated in the finer nuances of pure-blood society, Ginny wasn't entirely sure what was going on, but felt that her best course of action was simply watch and wait. She was fairly humored to watch Draco slip back into "Malfoy" and she hoped it was simply all an act. Ginny focused, keeping her face pleasant and neutral, going for the "Sweet women are speak when spoken to," theory.
"Most excellent, Mr. Malfoy," Matilda Prewitt droned on, seeming to be ignoring Draco's tone, "I must say, it's certainly a new day when I hear of such noble pure-blood families deciding to go into the service of the ministry."
She paused a moment, seeming almost as if the wheels were clicking in her mind, "Genevra dear, you must come for tea sometime this week. Your auntie would love to spend some time with you. It is high time you knew more about your Prewitt side of the family."
Ginny simply nodded, "I am sure that could be arranged, Aunt Matilda. Please send me an owl, and I will be glad to come."
Matilda Prewitt nodded and looked back at Draco, "Well, I hope this means you will be joining us again at balls. I hear this years St Mungo's ball will be quite nice. First one in several years, and I know the hospital greatly needs the help."