Sometimes small indents like that on a die can become ‘filled’ with grease or other debris so that the details don't get struck up properly during the minting process. Transitional examples can also occur where the impression is much smaller or lightly struck. This has often created the illusion of a variety among collectors who are prone to spot a supposed ‘rarity.’ I pointed this out* in the case of the 1 Franc coins of Ghent (Gent) Belgium during the German occupation (1915). KM has them as a variety with a dot present or absent. I found a transitional example with the dot very light which proved to me that it wasn't a true variety but a die state condition issue.
* In a paper I wrote for Numismatics International's Bulletin describing the entire occupation series of Ghent.