The Birthday Challenge section shows the caches you've found on the same day/month they were originally placed, otherwise known as... the geocache's birthday!
Previously, finding a cache on the day it was born (the very first/same day it was placed) counted toward this challenge, but this has been changed so that you actually have to find the cache on one of its true birthdays - one year from being placed, two years from being placed, etc. This rule change is more in line with the intended challenge and was requested by users. Thanks!
As always, please Contact Us with any questions, problems, or suggestions!