It sounds like Rhododendron Gall Midge. Young leaves rolled and distorted could be either chemical damage or Rhododendron Gall Midge, Clinodiplosis rhododendri, which are 3 or 4 times larger than a grain of Salt. The rhododendron gall midge is a tiny insect that feeds in the spring and causes distorted leaves to emerge. There is no way to undo the damage once it has occurred. Chemical damage should be associated with a chemical application (fertilizer, herbicide, deicing salt, etc.) and should affect more than one plant.

Another possibility is leaf roll and droop which is normal when rhododendrons are exposed to extreme heat, or drought. It is a natural reaction that helps prevent desiccation under these conditions of extreme stress. The roll and droop should go away when the extreme condition is absent. Since the same condition can be caused by root fungi which thrive in warm moist conditions, it is important not to over-water. If the soil is truly dry, then watering approximately once a week in normal soils may be helpful. Sandy soils require more irrigation. The soil should not remain wet.