It's encouraging that the newest leaf looks healthy, and that the damage is limited to the older leaves and hasn't seemed to compromise the midribs. The pitchers seem to be okay, too, as far as I can tell from the photo. It would be helpful, though, to see a crisp close-up of the terminal bud. If that is healthy, you probably have little to worry about.
It looks a little like some sort of chemical damage, but since the newest leaf is not involved, it leads me to suspect something else. I've seen my N. rafflesianas color up and crisp on the edges of formerly lush green leaves due to a stress reaction from a combination of excessive dryness and strong light (happened a couple of times when I forgot to water them–they drink a lot). This developed very quickly (like overnight), making the leaves ugly and hastening the demise of the pitchers on the affected leaves, but the plants recovered just fine.
It could be something like that. I wouldn't cut off the affected leaves as long as the midribs remain uninvolved and the pitchers seem healthy. Let them run their course, and keep the plant in very warm and humid conditions. I would also make sure the pitchers have fluid in them if they don't.