why are examinees, when left alone in the polygraph room for a long period of time, not supposed to look at the two-way mirror?
i recall that when i was left alone for like AN HOUR during my poly (that i was told i passed), after about 1/2 hour i looked at what i assumed was a two-way mirror and said "hello??"
It's fine to glance at the mirror from time to time, but making it obvious that you know you're being observed is likely to be interpreted as a challenge to the polygrapher's authority.
Your questioning after half an hour might have been taken as a sign of impatience, however, and may not have been a bad thing.