Hopefully she hasn't been poorly treated.I had the same happen to me about 2 weeks ago. Sudden text an hour before the appointment to say she’s taking the rest of the day off. I guess she either made her quota for the day or someone wasn’t nice to her.
I'd imagine that working daily takes its physical toll on someone. They advertise hours 11 am - 12 am every day of the week. Can't blame someone for wanting to take a break.