Over the years I have had two spawning events that I was aware of -- one was a BTA and the other was a Haddoni. In both cases nothing happened to my corals and the rest of the tank for that matter. With the BTA I was able to do a water change and run fresh carbon, with the Haddoni, all I could do was empty the skimmer cup.
So, if possible do a water change and run some fresh carbon, but if you can't I wouldn't worry too much --- unless this is a very small tank that is heavily stocked.
Could you give some specs on your tank -- size, lights, stocking and water parameters --- just to make sure that this wasn't a stress induced spawning.