I had a post about the nectar glands awhile ago. My truncata had round brown and reddish spots, like cigarette burns on boths sides of the leaves. Turns out that it was burn too much light and too little humidity. It was more shock from shipping than anything else - my plant recovered in about 2 months. It didn't have any pitchers at the time, so I couldn't tell you if the plant would stop pitchering if this happened.
Hope that helps!