I just went out and crawled under it. The shift linkage is mounted to the top of the transfer case adaptor so it's a rigid mount to the rest of the trans/adaptor/t-case assembly. Checked the bolts between them and all are tight. Plus, the shifter system uses a star gear and spring/ball detent which keeps it in gear. The linkage is still hooked up and the ball detent sits perfectly in the star gear. So, I don't think it's linkage.
I also just discovered that one of my transfer case bushings has over .060" slop between the sleeve and the rubber bushing. I'm wondering that when loaded up and releasing that I'm hitting somewhere. Problem is that's not what it sounds like.