She was being friendly and letting you know she might be responsive to you.
By saying what she did she was checking your SMV. She let you hear it though so she was giving you another big clue that she had noticed you.
She thinks that she was giving you some enormous signals.
Are there any other signals like partially turning her chair towards you, being a little louder around you, (ignore playing with hair, girls do this all the time), accidentally bumping into you, sitting near you when she doesn't need to, touching you for any reason, more eye contact than normal...
Etc etc..
If you catch her eye again and she smiles and doesn't avoid eye contact then go for it.
Alternatively she thinks you are a spazz and wants to know if she needs to get protection... LOL. I would go with the first one though.