How Doc changed

In the early years of Gunsmoke the character of Doc Adams was more hard-edged and hot-headed at times whereas in the later years he became more laid-back, softer and more gentle. It is not uncommon for people to mellow as they get older and I wonder if Doc's character was written to reflect those personality changes as one ages or if Milburn Stone adjusted his own acting portrayal to reflect his own softening persona. Not that Doc wasn't kind and caring in the early years or he didn't have harsh reactions in the later years but overall you can definitely see the more relaxed Doc later on as opposed to the early years when he would do certain excitable things like one early episode where Doc gets steamed up about something that he takes a gun and is going out to settle a score with someone and Matt has to take the gun away from him. You can't picture Doc in the later years doing such things or making such gestures.