Is a special outlet or wiring needed when replacing an electrical outlet under a gas fireplace.?
You can tell very quickly if the outlet is at all special by shutting off power to the outlet, removing it, and inspecting it.  

It seems rather unlikely to me that the outlet would be special since it's not near water, and it's supplying power for a blower.  Other than making sure you've got proper amperage rating, I wouldn't think there would be any special concerns here.