In-N-Out Burger complaint: Customer service

Hi, I am a very frequent customer at this establishment and am almost always met with such friendly staff. It was a bit upsetting when this was very much not the case this evening unfortunately. I was helped by a young man named Preston that was anything but friendly and I found it also odd that between working the order area inside the restaurant, he was laying his head down over his work area by registers. He was trying to make each item I ordered be the final item of my order. He then handed my receipt to me in a way that he was clearly irritated. I’ve never experienced this poor of treatment and I eat there or drive through most of the time I’d say roughly 5-7 days each week.
I am also employed in the food service industry and am sympathetic to having the occasional bad day while working my shift. I just have never taken it out on my customers as it is pretty unprofessional and makes the customers feel unwelcome.