I was thinking exactly what DM says. It's hard to be sure on my phone if wood vs micarta from the pics, but the surface is has such smooth uniformity it seems like a polymer, and the consistent white in the cracks seems like adhesive remnant (you wouldn't expect to see that in every crack in unstabilized wood), and the coloration is consistent with vintage micarta. Although the irregular rather than linear cracks are more consistent with wood . . . but then again, in paper micarta the layers are less pronounced . . .
Well either way, it looks pretty tricky to fix nicely - it would take some very low-viscosity (thin) and slower-cure super glue to actually penetrate into the cracks past the surface, and then require sanding and rough-buffing the entire bolsters. But those are some nice bolsters if you can make the effort! Or you could ask the maker to take that on.
If it is vintage paper micarta, it might eventually get worse, but not as quickly as unstabilized wood in that condition would do since as a uniform polymer it's less sensitive to temp and humidity changes than wood. And that stuff has to be from at least the 60s or maybe earlier, so it's been holding up pretty well and should probably continue to do so for decades yet.
