Lacquer paints work in a specific way- they mechanically bond to the previous coat (be it the primer, or another color coat) by melting the previous coat. It looks like your wet coat was a little too hot, and that melted the primer and the plastic underneath as you waited for the solvent to gas off, allowing the grain of the bare plastic as-molded to show through into your colour coat. You could strip it and start from scratch, you could sand it and re-apply primer, or you could sand the color coat and mist on a few more light coats on top and let them cure, and then hit it with a few more mist coats plus a wet coat that hopefully won't bit into the previous coats and bring the grain of the plastic through to the surface again. Was your primer compatible with the top coat you used?