Is it the evap core? Mine was having the same issue and they replaced the evap core under warranty. All good now.
2012 2SS/RS IOM, LS3, Aftermarket Hurst shifter, IOM interior, Borla "S", Big Flow headers, ADM Race cold air, BMR 1" lowering springs, All installed and Dyno Tuned by ARD in Houston, TX, 420 RWHP, 420 RWT
Added SLP Supercharger with stock pulley: 500 RWHP, 507 RWT