If she's smirking, nine times out of ten it means that your fly is undone.
What does it mean when a girl smirks at you? When a girl gives you the stare as if she's trying to figure you out, see if you're worth it? And when a girl gives you the look as if she may or may not like you? That's what I've noticed 3 girls do...
In this scenario... I always say the same thing.... Ask the person! Simple as that. Breaking something that isnt broken? If you dont want to ask maybe you arent sure you want to know in the first place.