A guy on a job in Toledo told me my weld prep was a joke

He pointed at a boiler header I was about to weld and said, 'Your bevel is maybe 20 degrees, you need a full 37.5 for proper penetration on this steel.' I felt like an idiot but he was right. I bought a proper angle gauge that afternoon and now I check every single joint. Has anyone else had a veteran call them out on something basic like that?