Given that Merle Haggard marked his 65th birthday earlier this month, no one would brand him a slacker if he decided to call it a career. Fortunately, though, Bakersfield's favorite son, who headlines at the Fillmore Auditorium on Sunday, April 21, isn't the retiring sort, and despite his vintage, he's in the midst of a late-period renaissance that's reconfirmed his status as a country-music icon with an independent streak an acre wide. A couple years back, he cut his ties with the Nashville establishment, signing with Anti-, a label whose parent imprint, Epitaph, is better known for punk-rock mayhem than for heartfelt confessions about how hard Mama tried. But rather than spiking his hair and duetting with Dexter Holland, Haggard used the opportunity to record a pair of shaggy, offhand, thoroughly enjoyable discs -- 2000's If I Could Only Fly and last year's Roots Volume 1 -- that make zero concessions to the distressingly banal "hot country" marketplace. Ol' Merle may not be fashionable these days, but his music's built to last. And so is he.