That tweet made me wonder if she talks in a lower register because it makes it easier to hide her accent, she sounds slightly British there, and Gossip Girl viewers always used to joke about Ed Westwick whispering his lines when he had to speak in an American accent. Gillian obviously doesn’t have a full blown British accent, but she has lived there for a long time and filmed tv with a British accent, so maybe it doesn’t feel as natural any more to go back to her old Scully voice
