According to a newly released report by AZCentral.com,Metallica cut their set short for the September 1 performance over at State Farm Stadium in Glendale, Arizona. The show was a part of the band’s “No Repeat Weekend” which sees them doing two consecutive days with no repeated songs.
He probably caught it from that dog that snuck into their show.
https://www.cbsnews.com/losangeles/news/dog-sneaks-away-from-home-into-sofi-stadium-for-metallica-concert/