Yes, that is pretty common.
If all you have is a half log that is not the best hide for a ball or most snakes in general.
Check these out.
http://www.reptilebasics.com/hide-boxes
I use these and add moss inside. During a shed the moss it kept moist and boost the humidity giving the snake just what it needs for a perfect shed. During non shed periods I allow the moss to dry out before making it moist again.
It is also common for the first few sheds not to go perfect as you are still getting things dialed in and your snake may be adjusting too.