(T) front strut free play

recently jacked car up to look at front brakes etc, also noted bushes worn on wishbones so thats a job to do but one thing i did notice when car was jacked up on the body that i could lift the front strut / shock absorber up and down about 1/2 inch
when on the floor the strut tops have that gap between the top washer and the body when jacked up the gap has gone, there is no movement or knocking and the rubbers all seem fine.
is this normal ? what do you think ?
it loks ok there is no lateral movemnt and no sign or wear