Definitively.
Sudbury Solar Neutrino Observatory, a few years back. The "missing" neutrinos were there all along, but had undergone a "flavor" change enroute, and the early neutrino detectors were sensitive to only one flavor. The upgraded to detectors capable of detect all three flavors of neutrinos, and there they were, just as theory predicted they should be.
You sure this wasn't the M&M's factory?