Yes---the change in xorg caused the problem. I linked the nvidia libglx.so from /usr/lib/xorg/modules/linux/ to /usr/lib/xorg/modules/extensions/ (renamed the libglx.so in /extensions to libglx.so.bak). Restarted my system & now have direct rendering.
dean@debian:~$ glxinfo | grep OpenGL OpenGL vendor string: NVIDIA Corporation OpenGL renderer string: GeForce GTX 960/PCIe/SSE2 OpenGL core profile version string: 4.6.0 NVIDIA 390.59 OpenGL core profile shading language version string: 4.60 NVIDIA OpenGL core profile context flags: (none) OpenGL core profile profile mask: core profile OpenGL core profile extensions: OpenGL version string: 4.6.0 NVIDIA 390.59 OpenGL shading language version string: 4.60 NVIDIA OpenGL context flags: (none) OpenGL profile mask: (none) OpenGL extensions: OpenGL ES profile version string: OpenGL ES 3.2 NVIDIA 390.59 OpenGL ES profile shading language version string: OpenGL ES GLSL ES 3.20 OpenGL ES profile extensions: That is a "temporary" fix that works.