I've only recently started playing, and I have had quite a few rough days as I had trashed all my items to give myself a little bit of a challenge. Today I went and killed a chicken, look how strong I am, and butchered it. After I had walked away, about 5 to 10 minutes later I noticed in my skills chat tab these messages:
[03:19:44] Butchering increased by 0.0371 to 1.037
[03:19:44] Butchering decreased by 0.0371 to 1.000
In the same time it took to increase the skill, it immediately decreased. Very peculiar indeed.