Why did she smile laugh a little when I asked how she went on an assignment she had?

She is a girl I get along with very well. We have just naturally hit it off. She was telling me last week that she had a presentation due this week for her studies. I asked her today how it went and she giggled. She then said she got an extension cause she was sick. I then asked if she is feeling better and she giggled again.
Why did she smile laugh a little when I asked how she went on an assignment she had?
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