Mike Gordon is no stranger to Nectar’s, the fabled restaurant/bar/live music venue where Phish played one of its first off-campus gigs in 1984. On Saturday, Gordon revisited his roots when he stopped by to take the stage with jazz-guitarist Melvin Sparks for a few selections, including covers of Lou Donaldson’s Everything I Play Gonna Be Funky and Sly Stones ‘Thank You (Falettinme Be Mice Elf Agin).’ Gordons sit-in was video taped and quickly uploaded to YouTube. The bassist will emerge for a show at Rothbury this July, while Sparks will perform at Babson Park, MAs Babson College on Friday.