Hi Gardener! Welcome to the Downs!
It's a neat observation, that Sam is the only one to truly return to Shire life. Pippin and Merry sort of do - they quickly turn their armour into party costumes - but you are right, they still can't quite forget what the armour is really there for, and periodically return to that higher life. I don't think their frolicking was a conscious effort to remind people of the Great Danger, their behaviour was actually more of a return to character of the silly sociable young hobbits. I think Sam was the one who actually took on that job, with the Red Book. I want to believe that it became a family tradition for generations past to be the scholars of the book and to educate the other hobbits about it. To have that story be their thing, like talking about Elves and Dragons was Bilbo's thing.