Okay, since I'm obsessive about things sometimes, I went back to the beginning with the RC-6 sheath, stripping all the mounts to examine it. I have found the issue I have been having.
It is coming from mounting the Tec-lock through the sheath rivets. Even thought the rivet holes are there and provide mounting points, when I mount the Tec-lok and tighten it down it is tightening rivets in the sheath sides as well. If I loosen up the top mounting screws in the Tec-lok it eases the pressure of the draw.
I didn't know mounting the Tec-lok could cause this, maybe others did. It makes sense but I didn't think compressing the screws tight could affect the rivets that much.
I'm glad others have posted experiences because it made me look at it and I learned something about the mount.