Why did she grab my hand?

My crush and I are friends, but not close enough to the point of making physical contact. So the story goes like this: My crush and I are in class together. I show her something on my phone but she can’t see it. Now normally, you would ask to hold the phone or tell them to place it on a flat surface, but she grabbed my hand and held it until she was done. She never or rarely partakes in physical contact even with her closest friends, but had no problem touching me. Is she interested or just being friendly

Why did she grab my hand?
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