I've been told that silicone or other common caulk materials do not play well with the "rubber" membrane roofing material on the slide. I had a leak develop on my '12 Greywolf in the same spot. 1000 miles from home, no less. I lifted the glass and drew a bead of Dicor sealant around the mating edge of the glass and laid it back down in place. Have not had a problem since, and that was 3 years ago. That window isn't going anywhere now, for sure.
2012 Greywolf 26RL
2006 GMC 1500HD, 4x4, 6L.
Chipped, K&N Cold Air Intake, Magnaflow Exhaust