something I received in email from mypoints:

As a California resident, you are not required to try Netmarket to receive your Free premium. To receive the premium, with no obligation to join the service, please send in a 3- by 5-inch postcard with your name, mailing address, apt. number, city, state, and zip. Please include code: TSCREEN. Send to: Netmarket, C/O USA Fulfillment, PO Box 4813, Chestertown, MD 21690-4813. Please allow four to six weeks for delivery. Only one premium per household.

California residents sure do get alot of special rules...The other that comes to mind is the "expiration date void in CA".