Maybe you guys and girls can help me with this one.....

I ran into a girl a month ago at a party (she's 28) that I used to date (she dumped me). I was with another girl and my ex was with one of her girlfriends. A couple of days later, I ran into her again (this time I was alone) and I spoke with her briefly. I could tell she felt awkward. I took the high road asked her about work and told her that I was glad everything was going well for her. Fast forward a few weeks....to yesterday.... I saw her at an alumni function. I honestly had no idea she was going to be there. She gave a huge smile when she saw me...I gave her a head nod, but didn't talk to her. After the event was over, I was talking to a buddy of mine (who she knows) as we were both walking to our respective cars. She was getting into her car, but turned around and came up to us and started chatting. I didn't say much to her...my buddy (who is married) invited her out with us to have some drinks, but she declined saying she had to be up early for work. I told her that was weak and she said next time. So, we get to the bar and surprisingly, she shows up. Funny thing is she didn't say much to me while she was out...instead talking to my buddy most of the time. When she was leaving she told my friend, "let's do lunch". But only said goodbye to me. I find this whole thing humorous. I didn't date this girl very long...it was casual (a month or so)....still not exactly sure why she ended things. I'm still thinking about what I want to do about the situation....I wouldn't be opposed to dating her in the future. I guess I am just curious as to what this girl is thinking. Any ideas? And how should I pursue her if I choose to?

Seems like she was trying to make you jealous bro... Invite her out to a club or something and bring 2 other girls with you. Make her jealous and she will chase after you.