Stockwell - My Sand Boa's used to climb as well. Only at night though, and as soon as they knew they had been seen they would dart for the sand. How only Sand Boa's can
As for my A.Maculosa climbing,
At first I thought it was because the terrarium was too cold and she was trying to get in closer to the heat. But I check my temperatures every 3 days and they are pretty much where they should be.
Hot side (Ambient) - 87
Hot Side Basking Spot - 91
Cold Side (Ambient) - 80
Night Time Drop - 77
As long as she is going to climb, I'll provide the space to do so. And I will admit that it is always nice to see her draped on her vines like a Morelia anyway!