Girl randomly playing footsie at work?

So yesterday at work I was sitting down in the lunch room talking to this guy I work with when this girl I work with came in and sat across the table from me. She never really said anything but started to play footsies. She was the one doing it, rubbing her feet on my feet and lower legs. I thought at first she wasn't aware of it but when I stared at her she just giggled a bit and continued. So I was just wondering what this was all about? I mean I talk to her and all but I just thought this was kind of odd.