I have heard of a few cases like that as well Greebo. I don't think it happens alot, The cases I have heard of is when you give the beardie too many meal worms. By the way you don't have to but your beardie into brumation, as long as you keep the temps up it will be fine - unless your friend let it go into brumation. I don't think that it would cause any problems anyway, but maybe a little stress for the animal. But I am not form down south, It's warm all year here.
Cheers