Gayle scored a hat-trick, including a 96th-minute winner, as the Magpies came from 3-1 down to beat Norwich City 4-3 in the Championship, sparking wild celebrations at St James' Park.
Summer signing Gayle said of Mitrovic's enthusiasm: "He shook my head. He suffocated me and he head-butted me.
"It was like whip-lash - I think he was trying to injure me!
"But he was just as excited as we all were. Those were unbelievable scenes at the end.
"Everything was just a blur for me. Everyone was going mental. It was unbelievable."