I was one of he older Captains at United and one of the younger new pilots that was hired before I retired called me oldman. He said it was out of respect because to him he thought that anyone my age with my experience and never having an accident or an "event" earned the title.
I didn't see it that way, but it wasn't worth causing a fuss over, so I let it go. Our Supervisor overheard him call me oldman one day and the next thing that I knew he was in the office, or as we called it, the woodshed. After that, I was called "Sir." So, I use oldman to remind me that it is out of respect. (lol)