Getting rid of a seam in Hard Shellac

I was attempting to do some solid body guitars with the Hardened Shellac. Timbermate pore filler in the wood, and enough shellac to get a nice even clearcoat. Let one month pass and now I have a seam on the glue line of the wood. You can see it from across the room if you catch the reflection right.

Can I scuff sand the shellac with some 320 grit, and use Behlen vynil sealer and lacquer on top of the shellac? I am eventually going to sell these guitars and cannot have such noticeable flaws. Please help!

is it the shellac that has left a line on application, or something else? In my limited experience, I'd be thinking alng the lines of a complete sand back and refinish. I agree, it's so frustrating when this happens in a finish.:(

I suspect the culprit is the glue on the seam. Some sort of PVA?
One of the nice things about shellac is that it's easily cleaned off with metholated spirits (denatured alcohol) and 0000 steel wool. I'd do that, sand back and refinish.