Dangit! Some error in the experiment was always the most likely reason, but we could hope.
hope for what, How the World Works by Scientists Who Demand to be Worshipped, Version: 49917912372?
Science is always more interesting when we discover that that our view of how the world works is shown by more precise data to be insufficient, for it opens up new fields of inquiry. Take for example Newtonian mechanics and Einstein's relativity. At the energies and speeds that could be measured in Newton's day, the two are indistinguishable. It wasn't until we began to be able to study high-energy physics that we were able to realize that Newtonian mechanics was insufficient. Until that was the case, there was no reason for us to even consider alternatives to a theory that fit all the known facts.
If Einstein had been born a century earlier, he would never have come up with relativity. It was an area of inquiry he would never had a reason to investigate.