Sounds like aphid or mites piercing the leaves to feed....the leaves crinkle in response to this....this will not hurt your plant.....just makes it look like bad...

Ian

I noticed the same thing this year, 2012, despite having the morning glory for the third season and in fresh potting soil. The leaves also attract a "bunch" of Daddy Longleg which do not seem to munch on aphids, so it has to be something else. The curly/crinkly leave has round black eruptions (for lack of a better word). Wonder if it is some kind of mold since the adjacent hydrangia flower also are turning black.

granddaddy long legs are called Harvestmen they eat decomposing plant and animal matter mostly, with an occasional slow-moving insect as part of their diet. sounds like aphids.
as for the black on the flower it is a form of blight. need to be careful as aphids carry viruses and beetles carry bacteria.

Thank you, Steven. Being in Southern MD, the summer mornings are only second to a quality Sauna environment.
Mold is definitely not avoidable.