Without seeing a pic, this is just a guess...when your cabinet was originally primed, (a good primer is FreshStart) the painter must have missed that edge or area. Happens all the time where the primer is often a rushed step. That would be a spot where it was needed the most.
It can be easily fixed with a light sanding, primer, then your paint color. Though after a few years, a color often changes slightly due to environmental exposure. On an edge it may not be noticeable. Give that edge an extra coat or three.
If you use the same cabinet maker, or even another one, just take that cabinet door in and they will fix it for you if you are not handy or don't want to bother doing it yourself. If they have the door at the same time they are painting your new cabinet, it will be free or minimal fee.
If you ask someone to come to your home or are asking to have it fixed otherwise, it becomes a time hog and often costs more than it should...travel time, fuel, paint dry time etc.
You probably have the color that was originally used?

Sleevendog - that was so helpful, thanks. I do have the color that was originally used. I didn't realize it was just an issue of priming, I had read somewhere about paint finish being "baked" or "catalyzed" to make it more durable. But that's probably with big manufacturers, not small shops.