In 2009, a small group of former Phoenix Theater dwellers now in their 30s convinced several local bands from the early ’90s to reunite; they aptly dubbed their efforts Nostalgia Fest. This year, the trick apparently bore repeating. Fifteen, Siren, the Wunder Years, the Grady Sisters, Kalifornia Redemption, Mainstream Trend and Truant try to feel young again on Friday, Dec. 30, at the Phoenix Theater. 201 E. Washington St., Petaluma. 8pm. $10—$25. 707.762.3565.