Isn't `lastSeen.age` a bit weird? If it's going to be mixed in with DateTime either through implicits or mixins, it isn't obvious what it is. I like this but maybe a better name than `age`? I think `oneMinuteAgo` is obvious.

Also, since this is an `Option` we will just have to do the exists again anyway.

`lastSeen.exists(_.age < Configuration.cookies.sessionExpiryTime`