Haven't seen that question asked in quite some time
The status check is only possible with a 13-digit CIS number. People who went through CP don't have that number. In theory, it is possible to get that number by calling a Service Center, and providing the person with the A#, so that they can give you the 13-digit number that is associated with the A#. In practice, though, that almost never works. First, it is nearly impossible to get through to any Service Center during business hours. Second, they usually say they can't find the A# in their system. It is a different computer system than their normal system, so it is more work to check it, so they usually don't bother...
So, the best thing is to just forget about it. The stamp is good enough for one year, and it has the same legal value as the actual card.