If it is under warranty, take it in. Sounds like you may have a leak of some kind. Check the ground where you park it over night and see if there is any evidence of a leak there. It has been cold the past few mornings here in SE Michigan. Something that may seal well when it was warmer may not be sealing as well now. This is the time of year everyone begins to notice their trans cooler lines leaking. Keep us posted.
2006 2500HD LBZ 4X4 CC/SB LT3, 265/75R16, Rhino Liner, PCV Reroute, Resonator Plugged, 35w 6K HID Low Beam & Fog Lights, LED Interior Lights, ISSPro Pyro, Boost, & Rail Pressure Gauges in A-Pillar, Cognito Idler/Pitman supports, more to come soon.
1996 K2500 Suburban 7.4L, 265/75R16, Brush Guard, Nerf Bars