Female Co worker behavior?

I have a female co worker who is in her mid 20’s and started acting different toward me recently. I am very introverted naturally. She started being more interactive with me, telling me that she wishes I would talk more. Walks pass me daily looks at me and starts smiling a lot for no reason. Then on occasion sees me asked me to smile I smile, looks at me and then she starts smiling. Is this friendly or flirty action?

Female Co worker behavior?
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