Gavin Rossdale and his Bush bandmates performed together during Saturday's Sunset Strip music festival in LA. Gavin led the vocals for the set that mixed up some of the band's old hits as well as their new tracks. The packed audience sang along while just off stage Gwen Stefani and sons Kingston and Zuma watched the show. Following Gavin's successful gig, the Stefani-Rossdale family also celebrated Zuma's third birthday yesterday. It seems Gwen opted to hang with her family this weekend in lieu of attending Kim Kardashian's star-studded wedding. Gwen was rumored to be one of the 450 guests invited to Kim's Montecito wedding along with Ryan Seacrest and Eva Longoria.