Animated character changes (when it shouldn't!)

I've built a slide with several layers that involves an animated character. The slide takes the learners through a series of 3 questions. The learner clicks a button to answer the question and is taken to the appropriate slide with the feedback and next question.

The animated character's facial expression and position changes on each layer. However, when I preview the slide, the character on one of the layers changes - her head appears to get slightly wider and she seems to move slightly to the right. But on the layer itself (no while in preview mode), this does not happen. I have tried deleting and recreating the character, the layer, the button that takes them to that layer, and eventually the entire slide. When I recreated the slide, the same thing happen, but on a different layer! I've also closed the course and rebooted the computer. Didn't help.

Frankly, I'm going nuts. The only way I found to make it so it doesn't happen is to use a character in the same pose (facial expression can change) as on the previous layer. If I change to any other pose, this happens, but only on that layer! This is fine for now, but I want to know why this is happening. Any suggestions are very welcome.