Why did she look at me like that if she already has a man??

So a few days ago I was picking my girl up from her job. When me and my girl was walking down the street her co worker jasmyne came up from behind us out talking to us. Then as she was talking to my girl I noticed she kept smiling at me frequently. My girl said she has a boyfriend so I didn't think nothing of it. Then the next day at work her co worker Jasmyne told my girl that she didn't mean to look at me like that. What did she mean by that??