it does give off an odor until it is completely dry.. i got paranoid about mine and have soaked it in 3 capfuls of prime in a cup, then air dried it and re-soaked it, because it still smelled..
then i realized it was the prime i was smelling.
On the phone with Seachem technical support today. After regenerating the Purigen you are not supposed to ever let it dry out or it can crack. Using it then could leave a precipitate type dust in your tank. I'm believe this is what happened with my tank. Used Seachem Clarrity and hung a Marineland Hot Magnum with a micron filter on my tank and it cleared up.
Discus Paul posted earlier that after regenerating it let it soak in de-chlorinated water until you are ready to use it again. It would be a good idea if Seachem noted the need to keep wet after regenerating on the product label.