It sure doesn't sound right. It sounds like maybe the seals are not gripping the valve guides tight enough,they are usually pretty tough to pop on.Tight to the point that if you ever pull one off you wouldn't want to reuse it. Is it a possibility the seals are for another diameter valve stem? They still shouldn't be so tight as to jerk the seals off of the guides. Any witness marks to suggest a spring is snagging them?Hard to imagine 12 springs snagging seals,though. Very odd. Keep us posted on what you discover,please!