Same here DS had grommets at three, came out before he was 5 and has had no problems in the last four years - it does help that he now has far fewer colds and his tubes are bigger and straighter so that the catarrh goes away easier and doesn't go to his ears.
Only realised both grommets were out when we travelled by tube one day and for the first time said his ears were popping as we went from the surface down under at stratford.