Nope, most people have their guns in an upright position. Look at the position of gun safes, gun display cabinets etc....
Try to re-zero, then stand it on its end fir a couple of days again. If it all goes to cock again, I would say the scope is more likely to buggered than the gun, but it could be that it may need a refil as Garf said.
Good luck and let us know how you get on wont you?
Phantom