sounds normal to me, They curl up in a ball when they feel threatened or insecure, so you must be doing a good job of keeping him happy, as for the climbing the sides of the tank, My guy does that exact same thing.. ALL NIGHT LONG.. he has 1 mission.. escape from that tank.. if its possible He'll get out.. (kinda like Houdini)
sometimes ill hear *THUD* as he falls over.. dummy.. and then he goes right back and does it again.
Completly Normal
Thanks for the confirmed ~ My BP did the same exactly as what you said. I am quite worry about this indeed.