>> The magnet may cause the real compass to be incorrect after storage <<

It should have no practical effect, as far as I know. While the magnet is in proximity, it will cause the compass to read incorrectly, but that is all.

Think about it a moment.

1. The compass needle is either magnetized or not - there is no "degree" to it wrt orienting itself to the magnetic flux - if the North end is polarized "South", it will seek magnetic North.

2. At the conditions in a PSK and the field strength of any portable fixed magnet, there is no "transference" of magnetism from the magnet to the needle - you would have to have repeated and consistent physical contact and movement between the needle and the magnet in order for that to happen. Example: Leave a steel needle near a magnet for several days and then test it - nope, not magnetized. Stroke the needle point-to-eye with one end of the magnet several times - yep, it's magnetized now.

Make sense?

Tom