The model we have for understanding the universe's fundamental particles is a bit like a gearbox: one tiny change to any one single particles' properties throws off the mechanics of the other particles, too.
So when a paper comes out that finds that the mass of one fundamental particle is off by a tiny bit from what was previously accepted, it does more than merely raise eyebrows in the physics world. If true, such a finding would mean that fundamental physics is "wrong" in some as-yet-undetermined way, and would shake up particle physics for decades to come.
