If it has been hot, it's possible. I also noticed that when winter takes too long, some pigs suddenly shed a lot for a day or 2-3, to get rid of the winter fur, as they give up on getting summer heat at some point. Well, their hair gives up, as hairs do stop growing after a while and then end up being shed. It should however not last longer than 2-3 days. Then other issues have to be looked into, like skin issues, parasites, diseases, etc.