Mloreg4

Hello, I have a 2008 Chevy Silverado LT crewcab Z-71. It only has 35K and is in great condition. I am thinking about doing some recreational towing behind my RV and so i was experimenting with shifting my transfer case into Neutral. I followed the instructions turning my key to on but not running position, shifting transmission into N. Slowly turning my transfer case **** to the N position and holding for 10 seconds. The N illuminated showing it was in neutral. (I wasn't sure what the owners manual meant or what was supposed to happen when if the engine is running shift the transmission into reverse or drive for one second to be sure if the transfer case if in neutral???, so i skipped that n left transmission in N) Regardless, i was quite sure the transfer case was in N. All was fine (truck transmission never left neutral, i went to shift my transfer case back into 2WD the light flashed for a couple seconds and stayed solid indicating that the transfer case was in 2WD. I shifted the transmission to park and started the engine. HERE IS WHERE THE PROBLEM STARTED-- i went to shift into reverse and heard a loud grinding noise. I instantly shifted back to park and the noise ceased. I shut the ignition off, then back to the on but not started position, shifted transmission back to neutral, and moved through my transfer case positions. ( 2WD, Auto, 4WD, then back to 2WD.) started the engine again and all was well. Shifts and drives fine now. I dont hear any weird noises but if anyone could explain to me why it is that happened, and if i should be worried? Could something be damaged or am i fine??
Thank you so much!!!