British Columbia: Rhodo leaves are curling up.....help, please

2 of my 30 year old rhodos put on a magnificent display of pale pink blooms this year. However, when the bloom phase ended, the leaves started to gently curl in upon themselves, much like they do when the temps. get too cold in the winter, or when they require moisture ( a number of weeks without rain in hot August can bring that reaction). I checked a number of sites trying to determine what may be causing the problem; I first thought it might be leaf gall or rhodo gall midge, but when I looked at pics of leaves associated with these, I rejected the "galls", because the curling on my leaves is not as dramatic, tight and crinkly as those associated with galls. Possibly it could be rhododendron borer, but I have not spotted "sawdust" from bore holes. Further examination is required.
As a side note, the rhodos had to be moved during a construction project 3 years ago, but they seemed to have recovered nicely. I am not sure if the problem could be related to transplanting 3 years ago.
I have not put soil or compost around the base of the bushes.
In the meantime, any suggestions anyone has would be appreciated.

 

Look into "Phytophthora" The spores could be in the soil for years, or they can travel in ground water or even the wind.

 

Thanks....will look into