Why is she outgoing with everyone except for me sometimes?

This girl is very out going except with me sometimes. For example yesterday I saw her she greeted me and then she got busy doing something, later when she wasn't busy she was laughing with our friends, I walked up and asked her to hand me something and she just gave it to me without saying anything to me. Then a few minutes later when they were gone I walked by and she glanced at me then continued doing what she was doing. I said to her "busy day today?" She nodded her head and said "yup" then a few minutes later she was talking to everyone and Being outgoing. Her and I are good friends and I did nothing wrong for her to not like me. What's up?
Why is she outgoing with everyone except for me sometimes?
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