Is this flirting i say it is?

I go to my girlfriends work to pick her up and i see her standing by the kitchen door(she is a server). a bus boy is standing in front of her.he is moving his dust pan and broom around kind of dancing my girlfriend is smiling then grabs the dust pan and says something and smiles, laughs.( i dont know what i cant hear them) then i beep the horn and she sees me and stops and walks away. when she gets in the car i ask her why she was flirting with him she says i as not flirting i asked what were you doing she says making fun of him cause his dust pan did not have a flap on it. now to me laughing and joking with someone is flirting. what do you think