Starfish question

I recently bought a Fromia starfish. I acclimated him slowly by drip over about three hours. It did well for a couple of days and then I found it on the substrate. It was curled up into a ball. No melting or disintegration noted. I left it there and just watched it. After almost a week, it finally unfolded and stayed there flat for another three or four days. Then it started to move around and now it is moving around my rocks and looks healthy. Any idea what is going on? It seems fine now but for almost two weeks I didn?t know what was going on or if it was going to live or die.