$60 overweight bagS

When I arrived at the gate they weighed my carryon bag with my handbag and computer. He said you bag is overweight it needs to be checked in. I asked if I needed to go back downstairs to do that and his reply was to go to the counter and pay $60 and they would check my bag in for me. I went to the counter the lady took my credit card payment then when she went to take my bag she said oh that’s ok you can carry it on. When I asked if I still had to pay she said yes and walked away.
What exactly did I pay for?