I know this is an old thread, but the same thing happened to me....with the same cage decoration/log hide. I purchase this from my local petsmart.
http://www.petsmart.com/product/index.jsp?productId=11147241
Even though I could not figure out how my snake would have escaped, I started setting tape traps. After two days of this nonsense, I went with my instinct...I carefully drilled a small hole at the very top of the hide. After all the noise and moving around, she came slinking out of the bottom of the hide.....In the blue.
Needless to say, this item no longer resides in her vivarium. It is near impossible to see this hole/access without turning it upside down and on an angle.
Just wanted to let anyone know this was not a unique experience with this item, but looks more like a design flaw.
-braingarble