Yep. Starts slow, even at a walk and then perfect this before transitioning to the next gait. It sounds like she's dropping a shoulder and 'banking' to the inside -- a common problem. Just concentrate on keeping her upright -- not dropping that inside shoulder. You can just pick up that rein and require her to 'stand back up' and keep upright. You'll get the feel of it if you realize you're working to correct that dropped shoulder.
Also be sure that you're sitting up straight and looking forward (not inside). Sometimes if we 'bank' inadvertently, we encourage that little habit. Good luck!!