Silvia pressure issue

Hi all, i have a rancilio silvia and a rocky grinder, when i just purchased the silvia i could produce good coffee while grind the coffee on 7level in my rocky, now days its seems that the silvia pressure increased, i have to grind on 2( very near to zero level). i know that the grinder is ok, because i grind for others on 8th level and its good for them, is there a possibility that the pressure went higher? how to check it?