Hi @andrea.costanza—I believe that those screws work in tandem with the springs to allow the pickup to be raised or lowered, so if you remove the pickup cover, the spring should be loose. Once you take the cover off, you'll be able to see how it all assembles, I think. You can re-seat the spring around the screw and then put it all back together. Easy fix (I think!).
The guitar probably took a bump during shipment and the springs moved—probably not a big deal, and probably would never happen again.