All Hell Breaks Loose - S3-E22
Visible crew/equipment: During the scene in the kitchen, after Piper reads through all the faxed interview requests, in the wideshots facing Darryl the reflection of the moving boom mic is visible on the glass at the top, center of the screen. (00:21:15)
Chosen answer: Her agent/manager negotiated a special billing as part of her contract. It distinguishes her from the rest of the cast, probably when she became a producer on the show.
JC Fernandez