They are fine. I have seen polyps taken from the same colony in my tank under the mh lamps change different shades when I propagate them in Lisa's tank with her PC lighting. I guess they change to suit their needs.
Mine are in a pretty high flow area, right in front of the corner overflow, but they are not getting blasted or anything. Just nice and steady flow across them. They are also near the top under a lot of light, previously 560W pc, now 260W pc and 500W MH (6500K) . They never changed colors when I switched the lights to MH. I also have more frags of them in a frag tank that also has a lot of flow (but it's different than the flow in the main tank) but only 130W PC and while the color is still the same the frags "feelers" are not nearly as long as the mother colony. The frag tank is 21"W x 16"D x 9"H so with 130W pc there is still a lot of intense light. It has a Mag 5 on a closed loop and the return is fed by a AM2100, which also feeds the other 3 tanks as well. I'm guessing that your light conditions and water flow are the reason for the feelers being "shorter" and the lights are the reason for the color change. I have corals that have completely changed colors from when I got them because my lights are difeerent than the lights they were under originally. Also the same coral can look different "colors" under different lights HTH
According to Eic Borneman in his book "Aquarium Corals" (pg. 121), he's talking about Pachyclavularia violacea (green star polps) and says...
"There are many reports of iodine additions (in the form of Lugol's solution) causing an adverse reaction in these colonies, often leading to a lack of expansion or even colony death. It is not known why this occurs, though the strong oxidizing properties and reactivity of elemental iodine may be involved."
You might want to cut back on the iodine and see if they expand better. Just a thought.