From what I understand you're referring to grinding all the way up to the spine? I think that's what you mean. Far as I can tell it isn't so much a performance issue as it is a cosmetic thing. Leaving a space from the top of the spine to the top of the grind line is showing your attention to detail, especially when you get both sides matched up perfectly. One way you can fix it if you do break the spine is by taking some 50 to 80 grit paper with a sanding block and sand the spine, where you want to show a space between the spine and the top of the grind line. You want to sand it flat, not with the angle of the blade grind. Did I explain that well enough? Getting perfect grinds also shows the ability and talent of the knife maker, it takes a lot of work, practicing, and a lot of grinding to be able to do it well each time.
There are ways to get better faster, I think Fred Rowe's Bubble Jig is a great tool, but I don't use it to do all my grinds, I use it to help me with learning how to judge my angles. It's a great tool to be able to do a a beautiful grind, but using a jig like that takes practice as well, and for me it has been more of a learning tool than a crutch as some folks like to call jigs. Being blind in one eye I guess I need a crutch, because my depth perception is extremely bad!
Either way, you still have to practice, you still have to learn and it will take time, the best tool you can have to be a knife maker is perseverance! The never quit attitude is the key to becoming a great knife maker!! Just my 2cents, hope I helped, Rex