Is it normal if a cats poop is growing hair?

My cat was attacked a few months ago by a animal. He's recovered fine, he has his personality back and everything; we found out recently his butt is reallly sore for some strange reason..My mom went to clean the litter box and she found hair growing out of the poop, she said it wasnt there b4 but now its like really long. It's not fur, but like human hair. I told her "maybe he's bee swallowing some of our hair??" she denied it and said its actually growing out of it. im trying to stay positive bout this, and she keeps saying no. is this normal? what do u think it is?? if u have any idea plz tell me..