Not common but possible. Hopefully there is no other problems causing the axle seals to leak. AKA if you had an issue w/ the differential that allowed the axles to move around a bit, then they would most definately leak in a short period of time again.
speaking of axle seals, I have had my car in a trans shop because I broke the input shaft. I have been waithing for 3.5 weeks for the damn thing because the tranny's axle seals have to be replaced when they tear open the tranny. Talked to dodge and the damn part is on back order because of the large number of trannys that have had issues.