It still happens, actually. Only a few years ago it was extra wet and warm at some mountain passes here, so it grew more mushrooms than normal, and that mushroom absorbs cesium-137 from the ground, which then ends up in the reindeer in bigger concentrations. Just checked, and it went from 201 becquerel per kg meat to 1301 the next year. In 2019, more than 30 years later.

Still below limits for what can be sold and eaten here (3000), but shows how big the fallout was that it still shows up decades later.

It's not easy being a reindeer, the populace where I live recently had to be killed and burned due to a prion disease.