Rubber Stamps End With Year 2012

I order all the supplies for my USPS station and today ordered several rubber stamps [the kind that have the rotating wheels which allows you to change the date from day-to-day].
These have normally been made [and sold] as five-year stamps... except this year. All the ones in my government supply catalog were made to last SIX years... and they expire in 2012.
Do you suppose we do, too?