My 3.2 SHO would not shift after coming to a stop at a light today. I drove it a few blocks moving the shift lever between Drive and 2ND, but with no help. I pulled over and had it towed back home. Once home I checked for codes. None were found. After a few hours, I drove the car around the neighborhood and it shifted fine. The transmission fluid looks and smells good. How do I fix this problem with no stored faults?