Freakish Facebook photo occurrence -- can anyone familiar with Facebook explain this?

Can someone please explain this crazy Facebook photo occurrence?

When you click on someone's profile, let's say, "John," you can click on "Photos," and then you're presented with 3 options -- "Photos of John," "Albums" and "Photos."

If you click on "Photos of John," you're presented with photos organized by the year they were posted by anyone else in Facebook, tagged with John in them, and are displayed in the person's timeline, in descending order, starting by 2012.

Note, they're displayed as to when they were posted (uploaded to Facebook) -- from what I can tell looking at multiple profiles).

If you click on any photo, it will display the photo, and to the right display WHO posted it, and underneath, the date within the current year posted.

Now . . .

What would explain the occurrence of 4 photos appearing in the current year (2012's) in John's profile (the only 4 photos in this year), 2 of which display September 15, and March 25 respective posting dates, as normal, but 2 displaying the same posting date of September 28, 2010.

When you click on the 2 2010 photos, you can click on the album they're from within the photos' Facebook holder's account. The album contains photos from all sorts of upload dates, and all sorts of people. The album has not been updated in 9 months.

How are these photos appearing?

If John was "tagged" recently in photos that were posted in 2010, would it not file those in the "2010" portion of the timeline??