What's wrong?

[Cabrera]

Hi fellow smokers,
A few days ago a friend of mine brought me some sticks from Spain, Montrecristo #3 and#4. They came in small packages (5 units each). As soon as I got them I took them out and into my humidor. A week later I can see that the wrapper has become kind of "bumpy". I smoked one today and allthough I was satisfied with the flavour and draw I could see that the ash was bendt and it needed constant "touches" with the lighter due to irregular burn.
Why is this? what can/should I do to prevent this?
Greetings from Oslo, Norway.