I was there, too, and a little shower came in during the last song. It may well have been lightning, but I also remember I had just pointed out to my buddy that I could see water falling from a hole or gap in the tarp, when "Bam" out went all the sound except dim drums. What amazed me was that when they restarted they just picked up right where they'd left off rather than start the song over. If it didn't lightning during the first set, I remember during the second set it was striking all around Carter Finley Stadium and we had moved up onto the aluminum seats--we decided that wasn't the wisest place to be.....
Richard