DD is 6.5 and still wets at least once a week.
Last year our GP said to come back and chat about it if it's still happening when she is 7. 7 seems to be a common age to get some additional help/advice amongst people I speak to (health professionals & other parents). Course it depends on how much it troubles you or your kid, I suppose. DD is sooooo blase about it, I don't think it'd be worth my while doing anything just yet.