Her thick glasses, her old- fashioned clothes, and her unidentifiable accent all gone off the impression she was from another place, another time. And maybe she was. Maybe she was a time traveler, a visitor from the future whose research was poor. She had studied carefully to understand the time but she'd gone too far back. The history texts got it close, but not quite right. So even though she was an amazing student, her facts were wrong and she didn't fit in. In fact she stuck out rather badly.
I suppose she could be from the past as well. The problem with that is that there would be no way to blend in. You would have no clue about fashion, or language. There are simply too many unknowns. So the future it is. She must be from the future.
Or, maybe she's an alien. She's from another world and she studied us by watching our TV broadcasts! She would then be out of date because of the distance she'd traveled to get here. No. If she was from an intelligent alien race who could get here, she'd have thought of that.
Time traveler from the future it will have to be then!