You could be right. Like any good mystery, several candidates are possible and have clues.

But right now one thing that leads me away from her is that as much as you might want to nudge people with your elbow, do you think that she will be a very dramatic, climactic, exciting reveal? If either she or Gaeta is revealed as the master Cylon, I don't see it as being as shocking or dramatic as the revelation of Tigh. More like Torrey and Anders being revealed as Cylons. It will result in a "Ok, I see it, she's been doing things all along, getting in close, watching etc." Not "holy frak!"

Characters that would result in a "Holy Frak" are Bill Adama, Roslin, Lee Adama, Starbuck, and maybe Joseph Adama, in that order.

Baltar would result in a different sort of reaction, but it could be turned into a Holy Frak by revealing special and astounding things about Baltar's true role in Cylon and Human history. A story that makes it all make sense why he is the one who betrays humanity, and then the Cylons and then, I suspect, brings them back together at Earth. The dramatic shocker will be Baltar's story, not his nature.

But unlike Baltar, Dee, Gaeta and various others are simply not set up to be part of a grand story. They are not the "chosen one." Starbuck is set up for a grand story. William Adama is. Lee Adama is. The minor characters aren't.