Fetching https://download.phplist.org/version.json?version=3.6.0 success

I am using version 3.6.0, and just recently I noticed this in the log:
Fetching https://download.phplist.org/version.json?version=3.6.0 success

It keeps getting downloaded - there are three or four entries in the log for every campaign. Why is it being re-downloaded? What does it do?

Thanks
Pance