Last spring I planted two new azaleas. One seems very happy, and has grown a lot. But I recently noticed its leaves appear speckled and whitish. See photo. There are no other signs of sickliness that I recognize--is this some kind of normal seasonal change in the foliage, or a disease? I have an older azalea not far away, and its leaves show a similar change, but less pronounced, and to no ill effect that I have seen.

The other is in a less shady spot and has unfortunately suffered from soil drying out a few times since I brought it home. It is also showing the speckled foliage, in fact more pronounced. So since the degree of speckling seems correlated with stress, it occurred to me it might actually be a sign of a problem. Please don't tell me it's deadly, tho!