Some toilet fill valves shut off abruptly. The inertia of the water movement stopping quickly can cause the pipe to move, if it is not anchored properly (this is called water hammer). Most manually opened/closed valves don't operate quickly enough to create water hammer, but things like your dishwasher, icemaker, washing machine, and toilet can. There are two items to look at: are all of the pipes anchored properly, and can you install an arresting device? The pipe moving can eventually wear a hole in it if it rubs on something, not a good thing to happen. A different brand of toilet filler valve may be less prone to cause a water hammer, too. My unprofessional opinion.