That's funny, this is an all too familiar story for me too. I've been at least a GM since I was 15 and I remember especially back then I'd frequently get surprised reactions and questioned by agents especially traveling on my own on how I'm already a GM and what not. Nowadays that energy has ramped back up with the surprised reactions and questions as a 19 year old DM, I can absolutely live without it but it's nice because whenever I get an agent like that I always feel well taken care of.