Newly-made gear sets get that icon (it's the item level icon) whereas older gearsets use the old item level notation since gearset names aren't changed automatically. If you change the gearset and re-register it I believe it should overwrite the old name with the new one.

Something similar happened the update when they added the average item level as before it would say, for example, WHM Lv. 80 only taking your weapon into account and nothing else.