Hiya
Yes, like Souffle has said, Agouti robos that carry the recessive husky gene do tend to get lighter with age as they tend to fade.
I have noticed that some of my robos and some of the robos i have seen photos of seem to have a more fuller, fluffier coat, where as other seem to have a more flat coat, and to be honest i ont know why! and i am still trying to document the differences to see if it is to do with age, genetics, sex etc. but havent really been able to figure anything out yet.
I always think that if you have the choice it is better to breed from robos that you know the background of, so if you are serious about breeding then it is a good idea to contact some breeders to see if they have any suitable robos available. but, one good thing with robos is that they dont tend to suffer as much from inbreeding like some of the other species do, and also they cant be hybrids, so breeding from pet shop robos isnt really as bad as breeding from other species from pet shops.
Like i said, i really would try to get some robos with a few generations of info, but it wont be two much of a problem to use your robo as long as she is completely healthy and capable of carrying and looking after a litter.
After all it is you choice
But if you need any help please let me know
Tammy x