I would check to see where your lights are running compared to what it was used to. It could be that you are providing too much light, or that the display that it was in when the picture was taken had different intensities of blue that would make it appear different. If it's open and the mouth isn't gaping it is more than likely healthy. But if it spends most of its time pulled into a rock and hiding it's probably too much light. Also RBT need to have live rock with holes to anchor and feel secure since their foot is vulnerable, if it's not getting that it could impact its color as well.