Mine does this when I let my truck sit for a long period of time (more than a week). I wait a few seconds then with my foot on the brake, I put the selector in each gear then reverse and back to drive. I've only had to do this 3 or 4 times in 5 years but that's what I do. I'm sure the torque converter is draining out and needs a second or two to fill back up.
JP
Jeff
"But officer, I ain't Speedin', I'm just flyin' low"
2001 Silverado 3500 Dually LS Ext Cab, 6.6L Diesel, Banks Stinger Kit, 4" Exhaust, VR Straps, Bilstein shocks, 255/85/16 BFG KM2s
2004 Suburban 2500 LT 6.0L 4x4, Bilstein Shocks, Federico front/rear sway bars
1996 Caprice 5.7L LT1, B4U Suspension, KYB shocks & Hotchkis sway bars, BMR RCA - alas I miss ya.
2013 Caprice PPV 6.0L