I've noticed since the last update, that when running through one by two openings or doorways, that my character will immediately jump, and continue jumping until i back up, and carefully walk through the opening.  I have also noticed when running down corridors, If my character touches a wall it will start jumping, and in some cases doing damage, if going down stairs. There does not seem to be empty blocks, or any other objects that cause the jumping. It has become very annoying though,  as I used to be able to move swiftly through openings, into my base, down corridors, or up/down stairs. As you know, the auto jump feature is very important to tablet players.