Does " Restringing " Pearls Mean Shortening?

by Dido
(Devizes, Wiltshire, Engalnd)

I recently took my 22" cultured pearl necklace for restringing at a jeweller I haven't used before. I've had it 12 years and had it restrung several times. It usually comes back a little shorter and stiffer - I expect that - but this time it has come back 18" long. That seems an awful lot. Is there a reasonable explanation or is it ok to complain?