I want to thank everyone who provided links and information on horses like the one in the previous post. I encourage those interested in this to read the comments section, where there are more foals with these types of markings. There are also comments on the Equine Tapestry Facebook page. Because some readers have had difficulty with WordPress comments (or links in them), I have gone ahead and put together a Pinterest board with some of the links in the comments. That can be found here.
It does seem likely that this is linked to the smoky cream color, which is a genetically black horse with two copies of the cream dilution. It also appears that most of these foals either lose the markings with age, or at least lose the strong contrast. Someone also shared a classic champagne foal with similar markings, which also faded with age. Classic champagnes are also genetically black.
This ties in with some questions I have had about how cream interacts oddly with the sooty pattern. I have been assembling photos for that post for a while now, and will try to get that up in the next few weeks.