It doesn't occur to me.
I can only think that either the screws are not tight enough, or there is another strange reason: e.g. oil between the surfaces of the fork steerer tube and the stem.
But first of all: If you have a carbon bike, it is compulsory to have a torque wrench :-)
Than you can look if the bolts are tight enough. The manual says between 4 and 5 Nm for these bolts, and that works with my p5. It should also work with yours.
I can only think that either the screws are not tight enough, or there is another strange reason: e.g. oil between the surfaces of the fork steerer tube and the stem.
But first of all: If you have a carbon bike, it is compulsory to have a torque wrench :-)
Than you can look if the bolts are tight enough. The manual says between 4 and 5 Nm for these bolts, and that works with my p5. It should also work with yours.