My suggestion is that the recents list saves your last play session so that if you forget to send a friends request before closing the game it isn't lost forever!

I have done this before and it sucks to miss out on friending someone who was really fun to play with!

I would recommend a small divider in the recents column that says "last play session" before it starts showing the ones that aren't from the current play session.

This means that you only have to store ONE play session worth of recents and then when the player closes the game all of the ones marked as old could get cleared like they normally do and you would only have the last play session's recents left for when you load the game up again!