I think I may have found the culprit.
When Facebook Won't Let You Add Friends | TheDolt's Blog
I found this on another site as well
2 days -- 7 days -- 14 days -- 1 month -- FOREVER
From what I've read it seems the general consenus is slow down the friend requests and cancel any outstanding ones.
Looks like you're stuck with POF or Plenty of Fucked up Bitches, I don't envy you.