I replaced the rubber valve seals and umbrella seals the intake and exhaust valves when I put the springs and retainers on I noticed the rubber o-ring seals slipped down the shaft of the valve stems is this normal or is something wrong here
thanks in advance

 

try putting the springs and retainers on first then the o ring seal then the keepers

 

Right, the O-rings go insode the retainers, right before you put the keepers in, their only job is to keep oil that ends up on top of the retainer from running down the valve stem.