There once was a time when dinosaur bands reunited only when the mortgage on the mansion was three months late and the royalty checks were drying up. But Crosby, Stills, Nash, & Young have reunited (a la Voltron) for their second tour in three years and, by all reports, it has nothing to do with a money shortage (right, fellas?). It’s because the band was so well-received on its “CSNY2K” tour that the old codgers decided to set aside old differences for the umpteenth time and hit the road again. This time out, it’s called the “Tour of America” and, by gum, that American tour is hitting our little hamlet. And Neil Young will be working in a number of his solo tunes, which is always worth the dough. (And if the cost of a ticket and some brews don’t completely empty your wallet, you can always head to the merch stand and pick up your official CSNY notepad, watch, or throw blanket. No kidding.) CSNY play at 8 p.m. at the MCI Center, 601 F St. NW. $43.50-$229. (202) 432-7328. (John Davis)