It can be a problem with any type of lighting and can vary from coral to coral. When increasing intensity/adding more light, it's best to acclimate the tank to the new light. HO
fluorescents can usually get by with shortening the photoperiod to a few hours a day and then increasing gradually every few days. MH
must be shaded from the get go.
Best suggestion when adding new corals is always start them off on the substrate or lowest point possible in the tank unattached. Ever few days move the coral upwards an inch until it's in the desired location and can be properly afixed.
It allows for better acclimation and should not bleach. Just be mindful when choosing it's permanent home in the tank it fits in with the species prefered intensity. That goes for any type of lighting.