Short answer, yes.
Explanation: Disney actual stores ALL Photopass photos for at least a couple of years. So those pictures that were taken last September are still out there, even if you can't access them. When you activate an AP, the Photopass system sees that and opens up your access to all your photos going back a year. So suddenly, you can see and download pictures from the past.
Now, that's the way it's supposed to work. Does it always work flawlessly? Well, no. We are talking Disney's customer facing IT systems here. If you're expecting to see something and it's not there, call. They'll find the pictures and correct the problem.
Steve