I would talk to a vet about this. My 4 year old cat started doing this a couple years ago and peed on anything soft, mainly blankets and piles of clothes we had in the laundry room. We took him in and it turned out he had an infection. We got the medicine to treat it, and he returned to using only his litter box. Definitely take him in to get checked in case there is an underlying infection or any other problem that may be causing it.