The gaps are caused because of sagging that can take place occasionally when a lot of toner is layered onto the label at once. The printing system/labels are not designed to handle large bold areas of coverage, and sometimes the extra weight of that coverage can cause sagging which results in a small spot or line that does not get toner at all (like you are describing). The system we are using is a cost effective alternative to more expensive labeling options that would force us to begin charging extra for the labels included in a stamp set.
It is worth noting that the index labels have been designed as a reference tool, not an exact replica of the stamp images. They are offered as a free perk with the purchase of a $15, $24 or $18 stamp set (we began offering them for sale separately only because of customer requests). If the majority of customers feel as though the labels are no longer playing a valuable role in the organization of your stamps, we can definitely discontinue including them if that is what you would prefer. We try our best to create a balance between offering you beneficial details, like the index labels, and keeping costs down so you get more for your dollar.
___________________________________________________________
This is in response to the complaints that the labels with the sets are smeared, streaked, or blank in places. One of my labels did not show 2 of the sentiment stamps.
