Not sure what you mean ... To me the "platty" gene seems to be the most "hidden" of them all, from what I've read ..!
I didn't mention platty 'cos it seems to be a totally different situation from that of the HG woma and the HG Citrus ... The platty gene actually does seem to be kind of a "hidden" one since as you say, the platty carriers DO apparently just look like normals (at least as far as I know, unless there's some secret marker trait that we all aren't privy to ...)