Don't you love it when they do that? My guys are too fat and lazy, they hardly ever wiggle any more, but I do get a kick out it when they do. Some will continue to do it through their entire life and others will slow it down as they get older, depends on the Leo but it is perfectly normal.

I've read that they do it to confuse the prey so they have a bit of time to grab it. I've read that they do it to attract attention away from the prey and themselves should someone else be looking at them for dinner.

Both make sense to me and maybe they lose a bit of that after a while in a safe environment.