I would think the primary hazard of using a flashlight in a combustible/flammable environment would be breaking the bulb, which in the case of an LED is not a concern. Next down the list would be contact closure arcing, which in low current applications should also not be a factor. If you are using a higher power LED or hybrid matrix, then the switch in the flashlight ought to be FM rated at the least. Beyond that, I don't expect much risk.