I like variations/errors/print defects/variants more than most folks. The red dot above the name on some 67 Mantles is a minor print defect. It has no official recognition in the hobby as far as I know in major catalogs or the registry, and therefore would not be on normal master set or Mantle collector lists. So I do not think one would pay a premium for it. Some might actually view it as a defect that detracts from value. Again, each to his/her own.
But I think they are kind of neat
If you check ebay you will see they are not hard to find