Grinder marks
Here are multiple suggestions:
Could be that you are not cleaning the edges well enough after grinding. After grinding and before cleaning, put them in a bucket of water to keep the grinder scum from drying on the cabs, and then scrub the edges really well when cleaning.
Also, make sure you are using a fine grinding bit.
If you are firing on “thinfire” try kilnwash. Many people report devit when using ThinFire when using Bullesys glass (oh! the irony! 
). Personally, I have rarely seen this problem, but I use Sys96.
If you are cutting ThinFire for each cab, but you have a fairly large ThinFire “margin”, the TF can curl up during firing and stick to the edges.
Dana W.
Jester’s Baubles Fused Glass Designs
