She’s Calling Corporate?

I’m a bartender for a corporate chain and one of my supervisors gave me a heads up that a customer I served a few days ago is trying to get ahold of corporate to file a formal complaint about me. She claims that I was “rude” because she sat in my bar for a few hours after she was done with her meal and I didn’t talk to her or check in on her as often as she would have liked and when I did ask her if she needed anything she always said “No thanks”. Mind you, she was typing on an iPad the entire time so I figured she didn’t want to be disturbed, plus I have to make drinks for the servers to take to their tables. My supervisor did listen to my side of the story and everyone on our management team knows I’m an excellent employee and that I’m not a rude or mean person and I always do my best to take care of customers. Saying this lady does call corporate, what’s the worst that could happen to me? My anxiety has been super high ever since I found out about it and I keep thinking I’m going to get fired😰