You're one HELLUVA lady. You took the high-road with class, and still managed to say what SO MANY in similar shoes are thinking.
It ISN'T your fault she's a bitch and likely a Karen, too. And as much fun as she sucked out of this First for you ... she has to live the rest of HER LIFE being ... HER, Firsts to Lasts. Being That Bitch in the worst way--the most cowardly way: trying to talk cash-money shit but to scared to either say it out loud or shut all way up and be polite.
All that many, you included, are likely to ever know about her is that the most civility she can dredge up for a perfect stranger who is a CUSTOMER ... is what she offered you.
She's not going to go far like that. She might not even be able to keep a job like that. Anyone who can't be at least civil while working in service never will. And she'll also miss out on opportunities that could have changed her life for the better because she rolled her eyes at the wrong person. THAT'S how powerful the bitchiness and Karenicity is for so many: It's more important than keeping their livelihoods and leaving the door to opportunity open.
She's a lost cause, but YOU? You're AWESOME and living your better life--hopefully soon to be your BEST life. And I wish you all the best.
Not that you need my wishing. You already know how to out-maneuver and out-class the riff-raff. Keep that shit up and rule the world, girl!