Congratulations and thanks for sharing.
Actually, I'm a little surprised we haven't seen more of this already. I did hear about someone in CA who reportedly produced an albino with a het to a pet store female some years back. I don't have the details and can't verify that story.
If a gene was randomly distributed at 1 in 100 would you consider it extremely rare or not? I'm not sure if mutant genes are really randomly distributed in the wild or not but if they where random, and a recessive gene occurred in 1 in 100 animals it would still not show up that much. That's because only 1 in 10,000 pairings would match up two of these 1 in 100 and since it's recessive only 1 in 40,000 of the babies would show it.
At one time I heard that Africa (Ghana, Togo, and Benin) exported about 150,000 wild bred baby balls a year. This may be a little high now days, I don't really know. At any rate, if a mutation was seen in 1 out of 40,000 they would get 3 or 4 of them a year. That might not be too far off for some of the more commonly imported morphs.
I guess my point is that I think some mutations may occur at rates as high as 1 in 100 in "normals". If you are using a het male, your odds of matching a compatible pair go up from the 1 in 10,000 in the wild to 1 in 100 (I’m assuming that this is a SK axanthic and not some new gene they both happened to be het for).
Given that there are a number of recessive genes, probably each occurring at relatively high rates, there is a good chance that in any sizable collection of "normals" there are some hidden hets. It's just a matter of pairing them with the right het or mutant male to expose the hidden genes.
So, here is an extra bonus to be had by outbreeding to normals. Just keep those gene carrier males rotated through your collection and who knows what you might find.