As u know Switzerland is one of the European countries that does not require visa for Permanent Residents. I didn't get my NP stamped in Zurich at all. The only stamp I've got was in JFK. I went into the non-american line and was told by the person who checks all your forms that I should've been in US Passport line. Nevertheless it took me 2 minutes to pass the passport control. My NP was stamped with "Admitted" stamp and that was it.