Cookie did this too, barking and pacing up and down the room at the middle of the night untill someone (me) got up and brought her to the garden for potty.
The dog school teacher advised to keep quiet when you bring her out, no smiling, nothing. Just let her go potty and bring her straight back to bed (Cookie slept in her basket but came in bed when we were asleep and never wet the bed).
She outgrew this when she was 5 months old and sleeps through the night now and if I let her she won't get out of bed until 11 am or so.
I'm sure she will outgrow this, but dogs easily make a habit out of this.