Zoa/Paly Question - Inverting/Over-opening?

[iCon]

What causes them to invert? 95% of the zoas/palys in my tank open fine and look normal but there's one frag of devil's armor that looks like the polyps are over-extending/over-opening. What's even more strange to me is that some of the polyps on the frag look completely normal and only some of the polyps are over-opening. I tried moving the piece around in my tank with no change

Can post a picture of this later but I doubt it's necessary with the knowledge base on here

 

[Roc]

IME some zoas will "over open" if they are in need of something like more flow, more light, etc