This is a great textbook case of the process of science at work. A key tenet of a dominant theory is called into question by an observation. Is the theory wrong? As Richard Feynman eloquently stated,
It doesn't matter
how beautiful your guess is or how smart you are or what your name is.
If it disagrees with experience, it's wrong. That's all there is to it.
On the other hand, what if the measurement is wrong? This is why we have replication and confirmation built into the process.