Yes, I also have discovered that I need a better place to keep my iPhone when I am in bed.
Not because of a lamp, but because my iPhone refuses to wake me up, unless I have to move a few feet to shut of the alarm. I go back to sleep too easily, if I don't start moving - so I keep my iPhone a few feet away - wakes me up now!
Sounds like there is something in that lamp that won't allow your iPhone to sleep (obviously).
Is it one of those touch-on, touch-off lamps? Maybe that's it.
Good that you found out that a few inches takes care of the issue