No, I don’t think it’s normal. Most people dress up for a first date – Yeshivish, Modern, non-Jewish. Normal is a nice outfit, heels if the height diff allows, and nice hair, makeup, jewelry and nails. I’m not saying there’s anything wrong with not being into that, but if it bothers you, she’s def not going to get any more into her dress.
If she was dressed nicely but casually, that could just be an age thing. When I came back from seminary, I dressed UP for first and seconds dates – wedding/shabbos wear. I’m 22 now and my friends and I go more casual – only clothes, not with anything else listed above. (I feel kinda dumb thinking back to 19)