Just before "30 Rock" had its premiere on NBC last fall, a bottle of Cristal Champagne arrived at the office of its creator and star, Tina Fey.
It was accompanied by a note wishing her well, from an unexpected source: Aaron Sorkin. Like Ms. Fey, Mr. Sorkin had created a show that was about to make its debut on NBC, "Studio 60 on the Sunset Strip." And like Ms. Fey's production, it was set behind the curtain at a place not unlike "Saturday Night Live."
While Ms. Fey said she regarded Mr. Sorkin's gesture as "classy," it did not mask the tensions between the two series. When, a few months earlier, a representative for Mr. Sorkin had called Lorne Michaels, the executive producer of "Saturday Night Live," to ask if he might shadow the cast and crew, Mr. Michaels declined. "I said, 'Well, Tina is doing that,' " Mr. Michaels, who is also an executive producer of "30 Rock," recalled recently.