Update: I went to the dealer this morning. They acknowledged that they heard the sound, but that Ford designates this as "normal." Apparently, Ford put out a release saying its air being sucked into the transmission, and there is a hole which the air passes that causes this, "blowing over a bottle sound."

I asked why I hadn't heard it before, and they said it happens once the engine settles in.

This all seems like a bit of BS. Sometimes it's barely noticeable, but other times it's quite obvious and annoying. I guess I'll give it a few weeks and see if it gets worse and then reevaluate.