Are you ever writing a number down or reading a number and a memory just hits you? I was just writing down the phone number to a local store I need to call and the last 4 digits hit me and I was like Whoa, that was the last 4 to my college dorm room. Who knew I still remembered that?!
ETA: September 29, 2012—As I am rereading this entry to add categories to it, I still remember the phone number: 774-4721.