I posted a similar post on a Azalea website through Yahoo,
This is my reply to that inquiry from George Klump ,Southern California Chapter, ARS/ASA

Thanks for asking this question. While you do not say what kind of azaleas you have, it is, nonetheless, the case that hybrids, as your must be, can revert to characteristics particular to one or both parents.

Here is an example. The original azalea brought in from Asia in 19th century, R. Coccinea, was initially reddish-purple with large dark green leaves, quite a spectacular plant. It was thrown out because it was not suitable for force blooming in the European flower trade. It was found that this azalea tolerated the sun rather well and became part of the group known as the Southern Indica azaleas. Suddenly, the R. Coccinea sent out a sport which had the same flower color, except that the leaves were light green. Nurserymen called that one R. Formosa. Right after that R. coccinea sent out a second sport with the same flower color, except that the leaves were smaller and were dark green as was the original parent, R. Coccinea. However, this plant was called R. Phoenicia after the general color and complexion of the Phoenicians of the eastern Mediterranean. [The flowers had a single red blotch on them.] Then, R. Formosa sent out a sport of its own which became R. Southern Charm and its flower was watermelon color. Still later, R. Southern Charm shot out another sport of its own which was called R.Judge Solomon which had a flower of salmon color, same leaves as R. Formosa.

Then, R. Phoenicia sent out a sport, large light green leaves, pink flower with darker pinkish-red blotch. Leaf size was large, as with the original R. Coccinea! That one was named R. George Lindley Tabor after a family in Florida which was well known for gardening work.

My point is that sports can occur anytime on any plant. It sounds as if you have that occurring on your azaleas. You would need to know the seed and pollen parents of the azaleas to determine which one is coming through at this time. This can happen with variegated plants which might shoot out a straight green branch of leaves. One must cut it off right away, else there is danger of the entire plant reverting to full green in time.

George Klump
Southern California Chapter, ARS/ASA