Stuck zip

her: my zip is stuck
me: have you been pulling on it?
her: no, just trying to get it up
me: so have you been pulling on it?
her: no, just trying to get it up
me: so you've been pulling on it then
her: no, just trying to get it up
me: no really, have you been pulling on it?
her: yes
She came back to me about 5 minutes later with the same dress and the same problem and the same argument. And this was at about 6pm on a cold night, when she had no reason at all to be fiddling with the zip of a summer dress.