"Given the year, I'm sure it's a bit out dated." And it was of course going to be Muggle attire. She wasn't completely unfamiliar with it - she had cousins that lived on the Muggle side of things - but she herself was never much for actually wearing it.
Still, she couldn't well stick to robes in a Muggle world.
"I don't want to put anyone out," she admitted nervously. Still, a temporary loan of clothing until she could get her own probably wasn't really putting her out.