Usually IGV do not have much dynamic stresses as compared to rotating blades just after it.did you inspect them also?
IGV just spin to give air required direction depanding upon load/ air fuel mixture etc.
normally during dust and moist enviornment, dust particle enter from fillter area and damage IGV paints surface. it looks like hair crack but better to remove paint surface before further.
if this condition prevail long time then there is a possibility of IGV airfoil crack.
where do you find cracks in your IGVs, i mean airfoil surface, its bush/pin area that helps it in rotating?