To me, Sam seems to be defending Strider in that apple-tossing incident. I was pretty impressed since Sam is so slow to trust him in the first place.
I think Sam is defending Bill, the pony they just rescued from Ferny.
'....And you, Sammie, don't go ill-treating my poor old pony! Pah!' He spat again.
Then Sam pops him with the apple. This ties in with the prologue's Concerning Hobbits
If any Hobbit stooped for a stone, it was well to get quickly under cover, as all tresspassing beasts knew very well
Bill Ferny must be a slow learner.
