En fouillant la FAQ Mirrodin, je trouve ça :
Citation :
If a permanent has no imprinted card, its abilities that refer to an imprinted card do nothing.
If an imprinted card is returned to the game (with a Wish from the Judgment set, for example), the imprint ability loses track of it and that card is no longer imprinted.
Donc il semblerait que ton Mox ne fournira plus de mana vert.