This small SERP update was reported and named by Search Engine Land.
Many website owners reported changes in organic traffic and its conversion rates on their websites. In most of the reported cases in this context, increases in traffic and significant decreases in conversion rates were observed.
Google confirmed the following day that an update took place, stating it was a separate update rather than being Panda or Penguin related, but did not provide any additional information.
More Information
www.seroundtable.com/google-update-not-penguin-or-panda-19773.html