Snows were originally line bred, which means that breeders selectively bred leos with the physical traits they were looking for until the offspring were what we would now call a "Snow". Being that they were going for a leo with as white a body as possible and a minimalized black spotting. Line-breds typically exhibit varying degrees of yellow frosting.
Mack Snows, however, have a genetic basis.
Anyways, along these lines, 'normal' leopard geckos (such as what line-bred Snows began with and diverged from) can be produced with varying degrees of lightness and darkness, varying degrees of flat yellow to deeper, brighter yellows (like how Tangs went the opposite direction and were selectively bred for a richer yellow, now quite orange, coloration). Your little beauty appears to have light coloring and it looks like she will retain that. This is why I'm guessing she'll be what some people call a "pastel".
Without knowing lineage, its hard to guess, but yes, right now it looks like she came from a line of leos that have been bred away from typical 'normal' characteristics, towards lighter body colors. Whether or not you would suggest this is part of the beginning of someone's line-bred Snow project or an outcross...yes, she might be, but you're right -- they are less likely to show up in pet stores.
Best guess is to check out the leos that could possibly be her siblings. That would give you a better clue as to how she'll mature, depth of spotting, degree of yellowing, etc.
That said, I still think she's a looker and I'm curious to see her in a few weeks/months.
-----
Too many Leos
1.0 feline "Spot"
0.1 canine "Tika"