I take it you do not work with metal miniatures often?

This is fine in the world of metal. In my other metal miniatures hobby I have several minis which are scarred like that. It is indeed not a big deal. You get a liquid greenstuff, dilute with water and coat like you will coat with a brush all the areas you want to have smooth. Or place a small line into the recess and smother with watered brush. Lots of ways to smooth out a mini. You can even take the sanding paper and gently sand if you want to.

I had to piece together miniatures which had GAPS between parts several mellimeters wide. This is nothing.

Remember that it is a miniatures hobby. So assembling and making your miniatures pretty is part for the course. By the price they charge for the minis? Totally worth a little bit of work.