It is common for my pigs to try to jump off my bed, couches, tables ect. For example, I had two males out. They did NOT like the scent of each other, and were partially divided from each other on the couch while I was cleaning both of thei cages. Well, I picked one of the boys up and the other boy (Simon) lunged at (Chubby). I dropped Chubby on the couch, and Simon lunged again. Chubby just jumped off the couch while Simon was going after him, and I took the bite. I still have the scar to this day. Simon got my main vein in my hand, and scratched with his front teeth while digging in with his lower teeth. My hand was bleeding severly for 10 minutes, and then little by little bleeding for 17 hours. I didn't go to the hospital- my mother used to work there and she gave me antibiotics and a butterfly bandage. It hurt!
Anyways.. lol, I got carried away. I do not think it is terribly harmful for piggies to jump off couches or beds, but just in case make sure the area is clear. If piggie did happen to jump and hit something, injuries could occur. You are much better off just keeping an eye on piggie and make sure he stays on. I don't let my pigs jump off from their own free will- if I am not looking and they get startled they may happen to, otherwise I am always supervising them on the couches.