Mike,
My recollection was that I went to the pre-stage area and was told no third round was mentioned, the volunteers were packing up there area, I went to talk with officials and was told no call was made at that time, I would guess the race director (Prez of SCTA) made a decision after hearing the status of the course nearing the end of the 2nd round and being racer friendly wanted to get racers another pass.
Third round was called and not many racers went to the line, I was ready and had my bike off to the side in-case a 3rd was called.
If you didn't listen to the FM/audio you may have missed it however people in my camp also heard it and went to the line to make a pass.
Hats off to the SCTA for putting on another great event, it was not great for one of my bikes however we had a great time as usual.
John