How do you read a random girls signals?

For example, I went to Target today and I saw this cute girl. I kind of gave her the eye but got nothing in return. She seemed to be using her peripherals(whenever I would run into her again) to look at me when I would glance over to her way. She then then left her friends( one boy and one girl) to walk to the restroom by herself. I was standing in line as she passed by. Was she trying to set herself up for me to talk to easily? Or did I think she was so cute that I just wanted that to be the reason ?