Why did she ask me what time it was, when I know she had a cell phone?

I walk into a building on campus a few days ago. Wearing my leather jacket, and feeling pretty confident. As Im walking up the stairs I see this olive-skinned girl, nice black hair, and just let a small smile show over at her. As Im walking passed her, she leans into me, and says, "Excuse me sir, do you know what time it is?" in a nice foriegn dialect. I said, "its 1:45" and showed her the number on my phone. I walked away. I realized there was a clock on the wall, and that she had a cell phone. This isnt the first time this has happened this semester with many girls.

Its never happened before. Is this a girl pick up line? And what should my response be after if Im attracted to them?