It was surely too late to get meaningful information from a necropsy. 7 years was certainly not "old" for a leopard gecko, esp. for an unbred female, but with her fancy
genetics, there's always a greater chance of other inherited abnormalities...more so than in those with normal coloration. I'd agree there is only a very remote chance
that this was anything contagious...I expect that others are safe. Just always sad to lose a pretty little pet so soon.