What do you guys think? Was she interested?

I was in the cafe in my college sitting by myself at a round table eating. Next, a girl came in and sat at a table directly in front of me and we made eye contact for like 3 seconds. After that I had got up and got another plate. After this I had gotten another plate, she was walking to put up her plate and caught my eye again so I nodded my head to her because I was unsure of what to say. My question really though is, does me making eye contact towards her show a sign of interest and was she even the slightest bit interested in me?
What do you guys think? Was she interested?
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