My puppy peed on me twice??

I have a 7 month old Beagle pup who is almost completely housetrained. I always let him on my bed since he loves playing around on it, I've been doing this for a while and he's never done anything. This week, when I was lying on the the bed with him near me, he came right up to me and peed on me (it was full-length peeing, not excitement pee.) I scolded him harshly and let him know I was mad. Today, he did the same thing, even though he gave me a look that meant he knew I was angry!! He is very attached to me, but not dominant in nature. He is neutered, and doesn't lift his leg when he pees (when outside or on me). Why does he do this?