Some pups might like the comfort of weeing in their bed maybe,my little Sheltie has done it on and off all her 12 years,I just make sure she has very washable bed or 2..The mum of the pups starts them off in their housetraining at about 2 weeks old when she gently pushes them away from her area and licks their tummies to help them wee, if mum wasn't too good on this the pups won't know they're not supposed to wee in the bed area.Try to watch him when he's outside to make sure he wees out there but never punish him for weeing where he's not supposed to it will just confuse him.