What could a random touch mean?

I was 11 on the bus going home and seated beside me was a woman in an all black niqab. We were both facing forward looking out the window ahead of us until she suddenly reached over to me and held my hand. When she held my hand she didn’t even look at me she stayed facing forward and it was odd to me. Then she got off the bus and disappeared into the night (nothing ghostly, she just blended in with the night). I did not know her or interact with her, I was just a girl on the bus. I don’t know if she was praying for me or something I’m not sure. Any ideas on what she was doing?