This looks the best place to ask this, although it's more a software than hardware issue.
On Facebook when you remove a friend I know they don't get a message. But what if you decide that deleting the friend was a rather rash decision made in the heat of anger and want to add them back. Do they get a new Friend Request or not because they already once accepted your request?
If they also deleted me as a friend I'd imagine that a request would be required, but I'm wondering if the other person didn't actively knock back my friendship (the way I did

) they might not even know I deleted them...