I'd put one layer of scotch tape on the no-go gauge. If it won't close on that then I'd go shoot and be happy. This is just to verify that the headspace is at least very close to your no-go and not way too long.
This is likely just an issue caused by a difference in headspace gauges. The gunsmiths gauge could easily be off by .002" from your gauge. As long as you resize your brass correctly this shouldn't cause you an issue for the life of the barrel.
If the scotch tape on the no-go still allows the bolt to close then I would contact the gunsmith that made the pre-fit and give them a chance to fix it.