YES!! I'm 22 days today and have been experiencing the same thing... to the point that my mouth hurts when I wake up. I've started sleeping w/ a gallon of water next to my bed so I don't have to come downstairs to refill in the middle of the night. Not sure if it's related to not drinking. I do know that there were several days early on where I was so thirsty (constantly drinking water but mouth still dry) I asked someone in chat about it- they said it was just my body rehydrating itself... which made sense to me.
I'm curious to see what others have to say about this.