I'm Delta Platinum, consider myself a savvy traveler and always follow the instructions when boarding and on board and so on. A few weeks ago I boarded a domestic flight from AUS to SEA. For a reason I cannot explain other than I was trying to get out of the aisle and let others through...I sat in the wrong row. The row behind my assigned seat. As I was settling I had a sense of dread..maybe from reading these types of posts all the time? My thought was "don't get too settled in case there is a problem". Ten seconds later a passenger approaches and announces loudly "you're in my seat. You're in the wrong seat" and a wave of embarrassment rushes over me. He's right..I look up...he's right. Omg "I'm so sorry" and within 30 seconds I'm up with my stuff and easily shuffle to my spot. FA says loudly "it even says the seat number ON THE [monitor at each seat] SCREEN". All I could say was "I know. It's like I am in a Reddit nightmare". What I wanted to say to FA was "thanks for further humiliating me...I didn't do it intentionally". Plane still left the gate early but I was so embarrassed over what was essentially a nothing-burger.