According to a study published in Geophysical Research Letters by University of Utah Guanning Pang and Keith Koper the earthquake that happen in 1959 had aftershocks in Yellowstone between 2017 and 2018. They also mentioned that these kinds of earthquake are very common.

For more info, please read the original article by Phys.org:
https://phys.org/news/2019-05-aftershocks-earthquake-yellowstone-.html