I'm so sorry you are already experiencing trouble with your new ceph. I know the heartbreak. I lost a few in the beginning myself until I got the hang of it. In my experience, the best way to take care of a ceph is to pretend to ignore it. Don't look at it directly, but only out of the corner of your eye. You can kill them with too much love. They like to be left alone and they really don't need to be fed that much. Less is more--much less. You also don't need to be filling the pitchers with water.
I agree with amphirion--back off the humidity and increase the air circulation (gentle air circulation), but I would back off on the watering, too. Cephs don't need to be soggy-wet, especially in winter. White powdery stuff sounds to me like powdery mildew. There were probably already spores on the plant, and the increased humidity just brought the fungus out. I would have said that you just had the benign symptoms of shock, but it sounds like your plant might be some real trouble.
Do not fear. It might very well pull out, but if you can't get it under control and it looks like your growth points are going to go, you might have to do some radical surgery. A crash happens fast so keep an eye on your plant. If the main stem rots you are sunk.
What I have done in such cases is to dig down around the main stem and slice off the entire crown with a clean exacto, taking a good length of the thick main stem. Then I cut off the affected leaves and pitchers of the plant and either repotted the entire crown or else divided it up to make a number of new plants. No rooting hormone is necessary. Then I covered the main plant back up and every time, except for once in which the roots had already been compromised, it sent up new growth in a matter of weeks. This has worked for me very well, and I haven't lost a plant in a while. (I tend to be proactive in this regard and take action sooner rather than later.)
Also, since you got it from a local grower, I would suggest you talk to the guy to get his take on it. If he has been successful in growing these plants, he might be able to offer you some helpful advice, and if you are good at putting a tear in your voice he might even break down and give you another if you lose it. And don't be too quick to throw away a plant that seems to be dead. Be patient. They often come back from the roots.
---------- Post added at 01:48 PM ---------- Previous post was at 01:12 PM ----------
It occurs to me that my last message might have been a little scary, and I don't mean to sound like everything is in the toilet and all hope is lost. I apologize for that. But do back off on humidity and watering, provide more air circulation, and watch the plant closely. It might very well be just reacting to new conditions. I have had them brown like that, even on some of the new leaf and pitcher buds, and they came back just fine after pouting for a while. However, if there is a fungus you will need to act quickly.
It would be helpful for folks to understand the exact conditions you are providing. Is the plant in an enclosure? Is it under lights or in a window? What are the general temperatures around the plant? How are your conditions different from the place it came from? Details like that are helpful in diagnosing a problem. Pictures would help a lot, too.
Cheers.