Urine Male guinea pig wet bum

My male guinea pig Eliot has wet, matted fur around his bum. Every thing else seems normal. He is only ten months old. Could this be a health issue or is this related to scent marking? They have a litter area and it is possible he shoved the bedding out of the way and then sat in the mess. I will wash his bum and do a boar cleaning today. Will post if I find anything new. Thanks