Still sounding more like a water issue to me. Good news is, out of the different types of bleaching events, the one you are experiencing is the "safest", for lack of a better word. Something stressed out the zooxanthallae within the corals and is making them leave the coral, which is making them lose their color. As long as it is just the color fading and no dead tissue and you still have good polyp extention, the coral will 99% of the time come back as long as no other major stressors happen. I have seen quite a few bleached corals like you describe over the years, seen quite a few reefers actually just about take the coral out and toss it because they thought they were gonners, but I insisted they leave them and within a month or two they all colored back up and look as good as ever.
The 2 really bad things to happen for SPS corals are 1. dying from the base up (RTNing) and 2. No polyp extension (usually related to water quality). If a coral is RTNing, fragging off good parts is usually the only way to save pieces of it, if there is no polyp extension for more than a couple days, something must be done to figure out why, but figuring out what is going on is critical before taking any action because playing a guessing game usually just stresses the sickly corals out more and causes them to die quicker. As an example, a friend has an ACIII controller that has both an OPR and pH probe. The ORP probe went bad and some reason that affected the reading of the pH probe. He didn't know this at the time and was getting very low pH readings (7.2-7.4) so he just thought it was an Alk issue (after checking his CA reactor and making sure that was working properly). He also did an alk test (incorrectly, which told him his alk was very low) and dumped a bunch of alk into his tank. He ended up killing quite a few of his corals from that because his alk was already 12, and he pushed it over 15 in a short period, which SPS corals really hate. So when bad things are happening, always do the water tests at least 2x to make sure the readings are consistent.
