I am not sure if I had the same issue as you, but my phone was in the charging dock, the screen would go off also. The first night it stayed on, the second night it turned off after a couple minutes.
I thought what could have changed, and finally remembered that I did not have wifi turned on the first night but turned it on the second day. I turned wifi off and the screen stayed on. Dont know why that made it go off, but now I just make sure wifi is turned off before putting it in the dock and the screen stays on.