Maybe this might help...
--- TSB "Technical Service Bulletin"
#10-06-01-007C: Active Fuel Management (AFM) Engine, Valve Lifter Tick Noise at Start Up When Engine Has Been Off for 2 Hours or More (Evaluate Noise and/or Replace Valve Lifters) - (Feb 9, 2011)
Go get your car checked by the dealer - There is a Service Bulletin for replacing the lifters that was issued. - see this post
http://www.camaro5.com/forums/showth...eplace+Service