This is most likely as a result of the shock absorber/strut lower eye mount being tensioned while the vehicle is off the ground on a hoist or jack stands i.e. the weight of the vehicle is not on the vehicle suspension.
The recommended procedure after fitting the shock absorber/strut to the vehicle is to only tension the eye mount finger tight. Only when the vehicle is lowered to the ground at normal ride height with the full weight of the vehicle back on the suspension should the eye ring mount be fully tensioned to the manufacturers recommendation.
Failure to follow this procedure can damage the rubber due to the twisting movement of the bush resulting in premature bush wear.
