Thanks for the help.  I found it.   I was using the micro binder clips to help hold the pieces together and I didn't realize that one of the 1/4" turns had a "short" on the outside rails behind it that the clip was touching (which also touches the inside rail nub).   It must have been bumped overnight.  I put some electrical tape on it and all is well now.

By the way, I recommend these clips very much as I don't want to screw the track down, so I clip them together and they won't come apart.  Must use the micro size though or it won't fit (also must make sure they aren't touching the ground rails).

http://www.staples.com/Staples-reg-Micro-Metal-Binder-Clips-Black-1-2-Size-with-1-8-Capacity/product_614400