I've seen similar responses in some of the corals I've purchased as well. My LFS tank has a 4bulb T5HO and a Marineland Reef capable LED fixture. It's waaaay more light than I have on my 29g and it's shallower as well.
But for some reason when I took each one of my corals home they all opened up much wider and inflated much more than they ever had at the LFS. I'm thinking their NO3, NO2, trates are high - or are high enough to annoy the corals.