Ball Python's Lower Jaw Issues

My ball python tried to eat a mouse tonight. He was only able to get the head and shoulders down & would spit it out and try again. This went on for quite a while. I finally noticed that his lower jaw was rolling backwards/inside out. I had to remove the mouse. Has anyone experienced this before?:(

Try offering the next size down feeder.

He ate a couple of hoppers tonight, but had difficulty doing it. We'll see what time does for him.