From Umphrey’s McGee to Earl Greyhound, Warren Haynes has always championed bands with young guitar-slingers. So it makes sense that Haynes not only brought Colorado rock-trio Rose Hill Drive on the road for a few days with Gov’t Mule, but also invited the group’s guitarist Daniel Sproul out for a mid-show jam. Partway through Gov’t Mule’s set at Danbury, CT’s Ive’s Concert Park on Saturday, Sproul took the stage for a cover of Neil Young’s ‘Cortez The Killer,’ a song he has played with the group on occasion in the past. Gov’t Mule will play a free show at Buffalo, NY’s Artpark this evening, while Rose Hill Drive will appear on Late Night With Conan O’Brien sometime after 12:35 AM (technically Wednesday morning).