Yep. I get this when during cold starts (not cold temerature, just cold engine) and I turn the blowers on immediately. Gas smell seems to vent into the cabin.
I have a 2004 with 15K miles, purchased Sep 04. It did this when first purchased and on two trips to service was told 'all is normal'. According to service, hooking to computer checks all 'emisions' and 'fuel' systems. Any leaks would be detected.
Well, it seems something leaks, but I don't see how I can pursuade service to do anything else... they're limited to what they can do (if they want to be paid by GMC) under warranty.
Northern NJ Larry
2004 Canyon 4x4 Crew (Z71)
Mods: Rhino-liner; Fire/Rescue Lights,
71 Datsun 240Z (project)
77 Datsun 280Z 2+2 (project)
1996 Kawasaki Voyager
1995 Yamaha Kodiak 4x4