a pickup works by sensing the various magnetic fields from vibrating strings, just like a cassette tape if you place a strong magnet next to the pickup for a prolonged period of time this will cause the particles to rearrange themselves accordingly hence spoiling the pickups/cassette.
oh by the way do not mix up the pickup rings for the bridge or neck if you removed both, if you look closely there are different planes at different angles to suit the arc of the guitar top. The edge(breadth if you look from the side) of the pickup ring should be sloping upwards from the neck towards the brigde.
As long as you use the orginal springs I foresee no problems with the tight compression, you can always trim the springs slightly to suit your own taste but exercise caution.